How to make character move on picture

[MKG93]

Hello everyone. I'm making one project ( Machinima ) and I'm new in Adobe Effects. So far I did learn some stuff and I love to work in the program. I want to ask if someone can giv me some tips or link to a tutorial on how to make one effect that I need for my project. Effect what I need is moving character on picture. I  allready have character that is walking exported from one program to Adobe but he is moving in one place and I want to make effect so its looking like he is walking on a picture ( from one side to another ) and then disappears. I know that probably this is easy to make but all I can find is how to create still character moving and thats not what I need.

Thanks

[ShiveringCactus]

Here's all the steps I can think of:

• With After Effects open, create a new composition the size of your final shot
• Add the video of the character walking to the timeline that has appeared at the bottom.
• Hit P to expose the position keyframes for the video 
• On the first frame, click on the stopwatch icon to create a keyframe.  
• Move the current time indicator along the timeline
• Move your character layer horizontally along.  This creates another keyframe
• Hit 0 on the numberpad and you'll see your figure move.  You'll probably need to adjust the distance the character moves or the positions of the two keyframes in order that it looks like your character is walking correctly and not sliding.
• Now - go to Layer ... New... Solid
• Create a comp-sized solid 
• And then use the mask tools to draw a box.  This will be the space you want your character to be visible in.
• Then use the Track Matte option on the character layer to select the solid.   The solid will disappear from view and the character will only be visible in the box you have drawn

[MKG93]

Thank you very much