click on frequently asked questions and look for leaf casting. There are some really good step by step instructions there

Leaf casting is fairly easy if you have the right leaf. The best ones are rhubarb, the blue-green hosta leaves and gunnera because they have very prominent veins. I like to keep my leaves in water to keep them very getting brittle and have used many of them several times before I have to toss them.

Just mound some sand on your work surface and place a garbage bag over the sand. Place your leaf on top of the mounded garbage bag, vein side up, centering around the mound, so that when the leaf is unmolded, you have a natural "cupped" effect. If you want the leaf to be flat, just don't mound the sand. Now take your hypertufa mix (my standard recipe is one part peat moss, one part perlite and one-half part portland). So in other words, if you use two scoops of peat moss and perlite, use one scoop of portland cement. Now scoop your mud on the leaf, working from the middle out. I usually make it about 3/4 to an inch thick in the middle, depending on the size of the leaf, and thin it out as I approach the outer edges. Basically, I just cover the leaf with mud, following the natural outline of the leaf. Now, I keep my hands off of it and let it cure for at least two days before unmolding. You're patience will win out when it's time to unmold. Just gently lift the leaf off the leaf off the garbage bag, supporting it in the middle with your hand. Turn it right side up and avoid handling the edges as they are the most fragile part. Gently peel off the leaf and admire your handiwork. You may want to clean up the edges a bit with a putty knife, but you don't want to wire brush. Check the gallery page for a picture of a rhubarb leaf table I made.

Thanks that was wonderful information. I think I might have a visial now on at least how to get started. Thanks again.

brookiejunk- First and fore-most use a dust mask when mixing the dry ingredients and use rubber gloves at all times. I've made many leaves and I've found if you want a nice smooth leaf to paint I find it best to use a concrete recipe like this one: 1 measure Portland cement, 3 measures (use empty can for measure) of FINE sand, 1 measure of cold water to mix too a 'brownie mix' consistency,(more dry than wet) Start out with small smooth leaves and as you feel comfortable with these go to a larger leaf. One thing more, immediately cover with thin plastic wrap and, after a few hours check the leaf and if starting to dry water mist lightly. After the leaf is removed mist ever 12-24 hours and add another covering of plastic; dry cleaner bags work great for this to hold the sides down tightly on all side, this to keep the leaf enclosed and moist. Very large leaves should not be turned till 24 hours or more, smaller leaves may not take so long-but don't great in too big of a hurry. Keep covered and water misted for 7 days. When adding your mix to the leaf avoid sunny and drafty areas or you 'crete' will crack almost immediately.
valolson1 also gave you good instructions above.
Good luck and have fun-Wendy

thanks again