A Glimpse of 3d

I started working in 3d for a few hours before going to bed. Here's what I have so far. A few changes are in the process of being made here. The main thing is having him come from behind the tree convincingly. I'll also have him take a few steps forward to get to his ending position and to slow down his momentum from jumping out. I'd like the final version to incorporate my drawing as the background so it would look like he exists in that "world". I'd like to paint the background and then light him accordingly. I'm not sure how I'll do that though. I'm really unsure of how I'll get my 2d background and his 3d body to overlap properly where the two interact. If worse come to worse, I'll more than likely just end up modeling the trees in 3d and simply rendering it out normally.