Do you mean Guild or Clan?
A Guild is a collection of players, gathered for the betterment of thier play.
A Clan is like a Guild, but in the fictional Clint City world. Every card belong to Clans. With the Clan a Card gets a Bonus.
To activate bonus to clan members must be inthe same playing hand.
To activate a guild a player must be (i think) over level 10. She/he creates it in the guild area. To join a guild you must be level 5 or over.
Hope this answers you q's