Here are some information about leagues on xpam, if you find some other intresting league please post here.
Lets start from public league:

Dotarank league forum at http://dotarank.com/
This is a low to mid skilled players league, you dont need any testgame or aplication to join this league, only thing you need is to install Client, its very simple to use http://www.dotarank.com/index.php?topic=5840.0 .
Good thing about this league is that they play tournaments very often almost every week, there are various teams there, but in semi-finals sometimes even in quarter finals there are very strong teams, so I suggest playing these tournaments first before going to any serious buisiness.

Dota private league (DPL) forum at http://www.d-pl.co.nr/
This is a mid to higher skilled players league, you need to get vouched in it by playing testgame or posting replay, however its harder to get in it than to play in it, sometimes you can find really good games while there are some bad games...
I suggest this league as step before joining safelist. They dont have any tournaments yet, but I think there will be some in near future, we could participate in it but I dont really know if we could benefit from it...
Same client is used for DPL as for dotarank.

Europe dota league forum at http://eurobattle.net/forumdisplay.php?f=419
Almost same as DPL but working on eurobattle platform, I am voucher in this league and I suggest it for testing your skill and learning!Tournamnets should be comming soon so dont worry and we will participate in it 100%.

Safelist league (SS) forum at http://eurobattle.net/forumdisplay.php?f=345/
Ok, now we are getting in some serious games, where every player have to do his best in order to win game. This is the strongest league at the moment on eurobattle.net, and one of the best leagues you can find at servers like xpam. Its not easy to get in it, you need to post request for vouch, after that if you got approved(by playing testgame or judged replay) you have to pass tiral period of 2 weeks during wich you have to play 7 games. Now this is the best place for learning, althogh sometimes capitans could be a bit too much demanding and expecting you to know things you dont, dont get depressed, you are always learning.
Safelist have some torunaments mostly team based, but they are aranging it rarely but it really is the top quality tournament last year finals were streamed live.

Thats all from me for now.