Q: Need to reattach the rear muffler

I was driving today (I work from home, so I don't drive very often), and a few miles away from home I started to hear my car pretty loudly, as well as a metallic clanging sound. I pulled over to discover that the muffler had fallen off at the area where it connects to the rest of the exhaust system. It was hanging on by the end on the back of my car. I called a tow truck to help me. He jacked it up for me and was able to help me remove the muffler completely so I could drive home. He also said that a bolt at that end had snapped, and that's why it broke off. He said if I get a new screw it should be fine. I don't have any idea how to put this muffler back on my car. What kind of screw do I need? Am I better off just calling a local mechanic? Any advice helps.