Think layers I would do a layer of the twigs on the bottom, maybe a layer of wood chips on top of that. then leaves, pumpkins, leaves pumpkins with wood chips on the top. Leaves, wood chips are browns, the pumpkins are a green. You need to mix the browns and greens. The reason for the twigs on the bottom is it will allow for some ventilation from the bottom, as well as good drainage. If you have a pile of good soil I would just spread that out on your garden site, you don't need the soil in your compost bin.
If you can go to the local starbucks that is a great sorce for a green for your bin.
You should never need to add fertilizers, anything store bought to your bins.
Good luck and welcome to the world of composting.
Sandy

I second that motion to leave soil out of your compost pile. Completely unneeded.

Deanna

Depending on how much material you have that may be a good size or too big or too little. Over time I have found that the optimum size for a beginner is the size Sir Albert Howard suggested, 4 x 4 x 4. The mixture, generally it is easier to get the right ratio by layering, needs to be pretty close to 30 parts Carbon to 1 part Nitrogen and the easiest way to learn to get that is with layering and 6 inches of high Carbon material, 2 inches of high Nitrogen material will get you there, a 3 to 1 ratio of C to N. Now all you need do is get just enough but not too much water in that mix and that is the tricky part.
The link below will connect you with a very good tutorial on composting.

Here is a link that might be useful: Florida Composting Online

On the contrary, the soil would contain the microbes and possibly some worms to start ingesting the garbage.
Definitely leave out the twigs and wood mulch....first because they tie up the nitrogen needed to effect breakdwon, and the wood takes forever to break down.
Even the twigs will take forever....even if they are buried deep.
If wood didn't break down over a long time, our houses would be in shambles in very short order.

The leaves are a very good addition...try to chew them up as small as you can. The more face of the material, the quicker it will break down.

The 5 X 10 X 4 is a good size bin...and it seems you have the material to make a good start ...you might though consider making two of them....one for the good stuff that you will want to separate from it and the other for added material.

I contend the pumpkins can be added as they are....including the seeds. Other posters have a different view about the seeds. They think little pumpky's will be made. They wont.
But they too, should be pulverized as much as you can.

But try to add material in a balanced way....too much meat and no potatoes makes for a lousy meal.
So add material in layers. What you think you shouldn't overload on, put that into bags and lay that nearby...it'll compost down in the bag some....and then use it over time as each of the other additions are added.
The soil can be given each time you add...the worms and microbes will attack the composting material as it becomes available.

The bin can have a floor....wood or cement tile...but be partial enclosing. You want the worms to enter from the bottom, but you don't want all the leeching of water to be retained in the pile so much, that just slows down the action.

The 5 x 10 x 4....might be split into two bins...5 x 5 x 4...
It should be close enough to a water source, yet far enough away from any windows or doors that odours could make a problem. Grass clippings especially when wet causes strong smells....so only dampen them and spread them out over and through the pile.

I respectfully disagree on layering. I don't think it helps and in fact mixing would have the contents in better contact with each other and prevent clumping from mats of like-materials.

I also disagree that adding soil helps boost microbe levels and kick-start a pile. I recently built a pile in sub 50F weather with table scraps and unshredded leaves that was 130F the next day after a sub freezing night. In the summer a pile will be cranking in a mere few hours.

Everything is already coated in the right microbes just waiting for the right conditions to multiply and feed (yes, that includes on humans... comforting, no?). I seriously doubt, despite the number of experts and texts that repeat that dogma, that soil makes it happen any faster- but a small amount won't slow it down. If it helps at all- it would be with the wettability of the pile at the expense of aeration.

Honestly- make a moist pile with enough greens, and it will be hard to keep it from composting.

Pablo yes mixing is the best way to go, layering is the second best and easiest way to start. When I start a pile it do layers at first then come back to stir things up a bit.

And yes as Pablo states, make a moist pile with greens in it and it will compost. Heck a pile of browns(leaves) will also compost on its own, just takes a bit longer.
Build you pile ontop the the soil, don't add the soil to the pile. The worms will come on their own, and trust me in they will climb up to their food if need be. Found worms 6 foot high once in a building I was helping take down. They had to climb up there to get there. Thought it was odd they were there, but I am sure they thought I was weird taking their home away. LOL

Wood will break down, yes takes longer than something like paper. Our houses don't break down in short order because they are not embedded in nitrogen and moisture. Well mine isn't as I don't really want to live in a mold/mildew ridden home. Both nitrogen and moisture help things compost, not totally needed, hence we see areas where houses are falling down. Yes might take a hundred years but in time even the wood in our houses will compost and fall down.
If you build your pile right you will never have an odor issue. If you have an odor issue you need to add more browns, adding a layer over the top will keep the odors in.I don't care where you build it, if you have an odor issue your neighbors won't be happy with you. Ever.
The best suggestion I can give you this morning is to read up as much as you can, reading the threads here is a really good start. Also doing some searches on the internet will provide you with lots of great information. But I love GW for all of the personal experinces that people bring to it.
Good luck and post a photo when you get a chance.
Sandy

Sir Albert Howard did think that soil, layed down in a 1/8 inch layer above the other two layers would introduce the proper bacteria to enhance digestion. today we know that the soil bacteria are not what does the digesting in a compost pile, there are other bacteria at work there, several species at different times. We know today that those bacteria are already present on the material we put into the compost, which is why vegetables and fruits will rot in the kitchen. So adding soil to the compost pile is unecessary.
Mixing the ingrediants is better, but for someone just starting layering can be of tremendous help in learning proportions, and once you know the proportions you can mix to your hearts content and get the same results. Often I still layer because it is just easier to get the right proportions in the pile and if you are energetic enough mixing can be done during the first turn over. When I fil up the compost bins in the fall, and layer, I find it often is not necessary to turn because by spring the compost will be finished, if I have things in the proper proportion.

2 inch by 4 inch mesh?

I use hardware cloth with a mesh of 1/4" so the material stays in. Even 1/2" mesh will have some material spilling out.

I use the 2x4 green coated wire fencing. Some spills out, but only at the top of the pile. The packed stuff stays put.