That is hard to say. I like the bedding to be about 6 inches deep. How much lettuce (or other food) to put in depends on how fast the worms eat it up.

If you are adding both at the same time to an established bin, you will want a lot of lettuce compared to the paper. The ideal C:N ratio is 30:1. Lettuce is about 25:1, while paper is about 200:1, and cardboard is 350:1, so it doesn't take a lot of paper to balance the lettuce. And odds are, there is already a lot of paper bedding in your bin.

Actually there isn't much. All I have in the been right now is some stuff that the worms have eaten and the coconut stuff that comes with the bin.
When I put the paper in am I supposed to wet it?

Whether to wet the paper is something else that really depends on your bin. In the past, I always have, but I have way too much water running out of the bottom of my bin. Lately I have been putting paper in the bin dry. It only takes a few days for the condensation in the bin to dampen the paper.

If you are feeding heavily with kitchen waste, you may not need to wet the paper. Otherwise, spraying it lightly should be enough.

Lettuce gets pretty wet its almost all water in mine I would do about the same amount of dry paper to scraps but mostly just by feel if it needs to be drier in there

One thing I've done with lettuce and other high water content waste is to go through a freeze cycle and then squeeze dry before adding to the bin. This can shorten the breakdown time and prevent a sudden release of moisture in to the bin when it does breakdown.

I'd use lots of dry bedding. It won't do any harm and will help avoid the results of the experiment linked below.

Andrew

Here is a link that might be useful: lettuce experiment

Intuitively imagine the lettuce in one hand and the dry paper in the other and how damp you want the final compost to be minus evaporation equals how much paper to add. Sort of have to imagine the decomposition process over time. This is maybe what vermicompostarists balance in their minds just before they fall asleep.

And I thought I was the only one who counted worms when I was falling asleep. I also think about the air flow through the barrel and layers of compost forming in hyperspeed time.