How to create guild?
First of all you need guild scroll - buyable in game shop for 85 points.
If you have an scroll head up to guilds
After you write name you will become a leader of guild.
How to invite players?
Head up to your guild managment panel and simply click invite
You can revoke invite using right click on invites tab
How to join other guild ?
Head up to guild managment and find desired guild. Switch members to invites then right click on your name.
You are member of a guild ;)