Do you think this is something I can fix on my own? I have no body work experience. What would I need to sand down the rust and what would I need to fill it back?

I found the same thing when replacing a windshield on my 1998 Trans Am. I found a local restoration shop that did a very good job repairing it for me. If memory serves me right it cost $300. Most body shops only do collision insurance repairs, you'll need to find a shop that will do rust repair.