If you can't find an answer here, check the web site and web boards for more help.
Teams create different buildings which unlock new, more powerful classes for that team.
You win the game by destroying enemy buildings. So it doesn't matter if you play Team Fortress, Capture the flag, Rocket Arena, or even Counterstrike. Yes, I put the file in the right place. Keep in mind this is a public test, so there aren't as many servers. The best place to look is the server page.