The map is divided into three teams, Bishops, Knights, and Rooks. You will be on one of these three teams.
To change to another team, open the clipboard and click the "O'Club" (Officer's Club) button.
Note: While in the Main Arena, if you change to another team, you will not be able to change to another team again for six hours. You must remain on one team for six hours before you can change teams again.
Once in the O'Club menu, click the "Change Country" button. This will give you a list of the teams.
Select the team you want, and click OK.