Damaged my garage - how should I repair?
If you want to do it right, it is a process.
 You need to start by removing the siding to get to the nails that hold the damaged vinyl trim to remove the whole piece. When that is off that will expose the remaining nails that hold the front edge of the garage door wrap. Remove the garage door weatherstip and that will either expose more nails that hold the back edge of the door wrap or the weatherstripping holds it without the extra nails. That should get you so you can remove all your damaged parts.

Get new coil stock to replace the garage door wrap and rent a metal break long enough to do the whole replacement piece. Make the same cuts as the original and nail back in the same locations, no need to be exact, but get them in the same area. Find the vinyl trim at you local builders supply and copy the same cuts and replace that and reset your siding that was numbered on the back side as you took it down to ease the reinstall process.

This is a simplified explanation. If you are game to do it yourself and do it right, ask what you need and you will get help.