There are a lot of events around southern California that are cheap to enter and good for new teams to get started. PBlyfe hosts a 3 man series at Camp Pendleton that is really affordable. Action Star Games has a tournament series. Almost Famous photography has a tournament series also.
Your team needs to look into creating an APPA account and an IDpro account for each player. Different leagues use different accounts. It is free to create accounts, but you may need to purchase an ID card for a league depending on which one you play.
For APPA, go to www.paintball-players.org
For IDpro, go to www.theidpro.com