Can I do my own capping on my outer garage door frame?

Question:Is there some kind of self sizing/install aluminum capping I can install by myself over the wood exterior frame of my garage door.

Answers:
If you are talking about the top of the frame, the material you want is called flashing which comes in aluminum and steel in various widths. You can buy a roll at most hardware, lumber, and home center stores.
It is very light weight aluminum and you should be able to shape it with your hands or two boards clamped together.