How to finish wood working project.?

Heres my situation: I just built a bar out of MDF board and it looks really good. I figured that I would just leave it the way it is because I know that if I paint it, I might mess it up. However, last night, I decided to put a nice cold beer on top of the MDF counter. Big mistake. Once I lifted the beer off the counter, I noticed that the water left behind started to create "bubbles." Since I am completely new at carpentry, I was wondering how I should finish the bar. Since MDF is not "real" wood, how should I treat it?