In relation to what you're asking, there are 2 types of tournaments in Country Clubs - free ones and premium ones. The premium tournaments charge an entry fee, and after WGT gets their cut, the rest is paid out to participants based on their results and what format the payout was set up with - either winner takes all, top 3 finishers or top 10 finishers... I believe. Payout would also depend on how many members participated in the tournament.
You don't have to join a CC to win credits in tournaments though. You can click on the 'TOURNAMENTS' link at the top of the page and play in any you're eligible for. But if you'd like to join a CC, you can click the 'WGT COMMUNITY' link at the top, then the 'COUNTRY CLUBS' link in the drop down. From there you can search and submit a request to join the club you're interested in, or post something in the Country Club forum letting people know you're looking for a club.
Hope that helps - Kelsey =)