The only way you should attempt the repair yourself is if your only goal is to stop and prevent further rust. If that’s all you’re looking to do, you can try to pound the bent part of the door frame to where it is flatter, sand off the rust, prime it, and paint it, but it isn’t going to look good at all. I’ve done that on several spots on my car, and it worked on all but one spot that had a deep dent that I couldn’t sand completely. I tried to flatten it out, but evidently, I didn’t get all the rust, because the rust came back.
If you want it to look good, you’re going to need to employ a proper body shop. Get three quotes and ignore the cheapest one, because the repair at the cheapest body shop won’t last.