first off welcome to SM

in order to get 3d elements into you video footage you need to have it on your PC as a series of tifs or tgas You then need to go through the process of match moving/tracking it. What this does is allow you to create a 3d camera which matches the movement (hence the name) of your real camera. This is done with either maya live / boujou / matchmover. This is a tricky process for a beginner but a skill worth learning. You wont get it right first time I assure you!! but stick at it.

You can then animate your character etc etc and render them with what is called an alpha channel. What this does is tells your compositing app where the image should be transparent. So in the simplest scenario you can then place the CG straight over the video footage (not in premier! you need after effects/photoshop (for a still) /shake etc) bear in mind if you want your CG character to pass behind someone/something you need to eiether rotoscope where they will pass behind to create a mask that you can use to make your CG hidden at the correct place. Also bear in mind that you may need to create proxy geometry to cast shadows onto etc for your CG character.

What i'd suggest is getting to grips with maya before you try anything like this, it's not a trivial matter especially if you've never done it before why not check out the free beginner video tutes here at SM to get you started?

Post again and we'll see what we can do to get you started ok?


Alan