[How To] Join a Division
 

[How To] Get Your Team Icon
 

Once you've been confirmed as a member of your team go to your 'User-CP' again and to your 'Group Memberships' as outlined in the above post.

At the bottom it will say "You may choose to be identified as a member of the following groups." Choose which group you would like to be identified as and click 'Update Display Group'.