I have a video where I insert a still (in another composition) in at the end of the video with 3d tracking. As the person runs away there is a point where he meets the still and his head is actually behind it. I cannot use the layering "bring forward" or "send to back" on either item as it messes up all the other effects or you just plain can't see it.
Any advice is helpful. I have posted a lot over the last few days. I am new at this and appreciate as much detail as you can give. Received a lot of great help on here so far. Thanks.
Here is a test of the video on youtube: 420 3 - YouTube
You really need to go through these resources: Getting started with After Effects
They will help you a lot with some of the basics like using layers.
In this case, you will need a second copy of your footage layer, place it above the lion in your composition, and use a mask to make it visible only where the head should cover the lion.
This technique is called rotoscoping. More info here: After Effects Help | Managing and animating shape paths and masks