If you mean the Wentworth event you may have read about, Mike Harris or another from GM will make a post for 'expressions of interest' whereby you email him with some basic details. Usually, the prize is unlknown at the time, but they are always top notch i.e one last year was c/f Wilson irons with P. Harrington no less.
The winners are usually decided on ability (i.e if they want a mix of handicaps) as well as contribution to the forum generally. As far as I know, no money changes hands
Best advice is to get stuck into the forum and you may get lucky!