Ah, you're come to the right place!
Most community run tourneys only need you to tell them your name and average, and maybe tier. Hopefully, if it's a well-run tourney, the runner will keep you 'in the loop', and tell you about recent events, what you have to do and who to play. Just make sure that when you do see a tourney, and you want to sign up, that you still can.
(I'm warning you now, shameless plug coming up) I just happen to run a link with every community run tourney, called 'The Community Tourney List' in this section of the forums. Have a quick look at it, might be helpful.
Good luck entering a tourney, I hope you have fun and enter one that works out!
P.S. If you want some more info, just PM me and I'll try.