Why will radio and overhead lights and horn not work on a 1989 Chevy Celebrity Ive already checked fuses and they just blow when I replace them?

If its blowing fuses, then you have a short in that circuit somewhere. Its going to be a tuff process of elimintation to try and find the short, but it will need to be dont to correct your problem. The best place to start is your cigarette lighter. The lighter could have a short, or the terminals on the back side of it could be shorted, or the most common problem, a penny has gotten into the cigar lighter.