How should i fix this?

 

I had the same problem on my 87 camaro. I cut the piece out and cut off a replacement at the junk yar and welded it in. It's not too hard. Just make sure you have it aligned good and dealup the weld good so that moisture can't get in there and do that again. You could also buy a replacement pannel from year one. I've never bouight one but I've heard that they're pretty good.

 

Sounds good to me. Thanks