Where is the Virtual Tabletop?

I have just created a game to try this site out. I created a game but cant access the virtual tabletop unless I start the game. How do I prepare my maps in advance before I start the game. I tried watching the tutorial but it starts in the virtual tabletop. Help! 

Just load up the game and work away at it. The game doesn't "start" until players are logged in and ready to go. If you want to make sure they can't see stuff ahead of time, leave the player flag on a landing page. They only see the page they're on. If you are worried about them reading the chat log, you can turn on /talktomyself to not echo your chat where others can see it.

And (if you have not found already) once you launch Roll20 you find the maps/tabletops in the upper right - a blue tab with a white page --Page Tool bar-- to add/modify/delete/etc. maps...

Thanks ya'll! That was VERY helpful!