How do I access virtual tabletop?

Hello there, I've just joined Roll20, still inexperienced then... I haven't joined any campaign yet, however, when I click on the virtual tabletop link on the top left side of the page it simply redirects me on the home-page of the site instead. Therefore I don't know how to access all the features and mechanics of the playing system... I've sought a solution in the wiki area but I didn't find anything about. Do I have to be a supporter subscriber to gain full access of the area? Or I will be able to access it solely after being accepted into a campaign? My laptop is a windows 7 and my browser is Firefox. Thanks for the help beforehand and compliments for the good job.

Roll20 is a tool, not a game. The reason you can't join any campaign is because you haven't joined any campaign. Try creating your own new campaign to see what I mean. Look in the 'looking for group' forum posts, or the 'looking for group' tool, to find a group to join. Once you're either in someone's campaign, or have your own, you'll have a tabletop to 'play' with.

To add to what Phnord said, after clicking "Virtual Tabletop" you should see a list of campaigns you have joined. Additionally, there is a blue button to create a new campaign. If you have not yet joined any campaigns I suggest creating your own to get used to the features.

Ok got it... Thanks for the help! Sorry but I'm pretty a newbie still!

No worries... you'd be surprised how often this question (or some variant of it) is asked!