Hi! The only "try out" is to play a bunch of games with the other players until you get good enough to play more and then, eventually, you start getting picked for WDL teams. It's kind of like the minor leagues/off-season. We call this "private ctf". If you are familiar with irc, #wdl on irc.quakenet.org is the place to be. Most games are organized here and there are plenty of people to help you get started.