There are no clans or guilds right now, at least not implemented in the game at all.
If you would like to add yourself to a clan check this page: http://wiki.themanaworld.org/Guilds
Victor wrote:if there is no guild os clans... how can he join himself????
Because you can put your name in one but game-wise are not implemented and you can't do anything different what you already do alone. In other words, guilds at this moment serve for nothing.
I will be working on the join guild feature soon. For now it will be wiki bases but once we get the new server done we will be working on the guild system. To join a guild ask the guild leaders. To see a list of the guilds you can always check the wiki page titled, guilds.