Yes you can fix it yourself but I do not know how handy you are with tools and paint.
You need to straighten the sheet metal first. The gentle you do it the less you have to fix. I would warm up that corner using heat guns one on each side (a helper is recommended) . Warm the paint but do not bake it/damage it! (warm paint is much less likely to crack and peel). Once it is warm try to push the metal back using something like wood wrapped in cotton (no synthetics that melt). You need the cotton so not to damage the paint. Even kitchen paper towels are good. Try applying pressure on large areas not on the edge of the panel. Take your time and learn from how the paint and the panel reacts. If you are lucky it may bend back without cracking the paint too much. Keep the panel warm by periodically heating it up. Test the temp with your finger as your thermometer to know when to apply heat again. Finger crossed you can bend it good enough so you can live with it. If there is a crack in the paint try to touch it up. We can provide info how to when you get there.
If the above doesn't get results (e.g. the metal is too tough for the force you are able to apply) then you either find a stronger helper or go to second method that is pretty destructive: hammers, anvils, and pliers. You will have to do body work after to make it look half decent, use bondo or the like to cover the tool marks, sand, prep, the whole thing. As always start small and increase the amount of force as needed. For the big bend do not hit the metal directly with the hammer. Use something in between that will spread the force of the impact on a larger surface. You want to bend it not to dent it. You do not want to make more work for yourself. Provide support on the other side for the gate that is not bent so it does not get deformed. You may need to make some improvised tools/supports out of wood as needed.
Given that you do not have experience with this to know where to apply force to get the results you want, take your time and experiment slowly. If you see that the panel starts to deform in a unwanted way, stop and think how else you should do it based on the experiences you have till now and on mechanics (e.g. physics) knowledge you have of leverages, deformation, etc. Try to do the big changes first and worry about the small stuff later. Some things just get fixed in the process automatically while some things get broken again.
You can also end up messing the panel more especially if you are impatient or do not pay attention. That is a risk you will have to take. If you get frustrated take a break and come later or you'll surely going to make a stupid mistake.
It can be fun like a puzzle or origami, and quite rewording but it does take time and the results will not be like going to a body shop. As long as you have the right expectations all is good.