Roll20 makes no sense

How the heck are you supposed to use this thing? 

Roll20 is a virtual table top that allows you to play games (mostly geared toward rpg's like Dungeons & Dragons, Pathfinder, World of Darkness, etc.) with other people using only a web browser. Roll20's table top includes common tools to help make that possible.  This is a good place to start:  Helpful Hints, Tricks & Guidance Thread Repository If you have any specific questions, just ask. Cheers

Introduction To Tabletop RPGs

And of course, the interactive Tutorial will help greatly in getting familiar with the basic features of Roll20

"Specific Use Questions" is meant to be specific. Could you specify what the issue is? Do your miniatures not fit on your PC monitor? If you need guidance, I'm sure plenty of people (or the resources above) can give you useful information.