Are you referring to these groups? https://prntscr.com/o6oyiq
Those aren't special forum groups. Those are community groups created by members. Only official groups have official titles like that. To view all of the official groups and titles, you can take a look at this thread.
https://www.mpgh.net/forum/showthread.php?t=683570
If you want Premium Member, you can check out this thread to find out more about donating.
https://www.mpgh.net/forum/showthread.php?t=455710