Questions on pulling out a hit bumper...

Hey, all. The previous owner backed into something with a little bit of force and knocked the right side of the rear bumper in. I was wondering what the procedure would be on getting it kicked back out. The bumper is still in good shape.

Also, does anyone have a right tail light bezel they would want to sell me cheap? And are the gaskets necessary for reinstalling the bezels and tail lights? Do you put some sort of shellac or sealant on them when tightening them up?

Thanks, everyone! This forum has been awesome at answering my questions!