Need Input. What Do I do now?

Hey whats up guys. I need a lil help. I welded new quarter panels on my coupe about 2 weeks ago. I was told by some people to do fiberglass, then bondo. Someone else told me not to use fiberglass. What do I use? Any help would be great. This is what it looks like now. This is just bondo. (not finished yet of course)

