There are two ways to join a group. First, you may be added to the group by the group moderator. This is not controlled by the user, but by the group moderator through the group control panel. This is the only way to become a member of a Closed or Hidden group.

To join an open group, click the small Groups link at the top of any page.

Choose the group to join from the Join a Group dropdown list shown, and click View Information. This will take you to the Group Control Panel. Click Join Group to request membership in the group. The Group Moderator will receive an email informing them of the request, which they must approve before you become a member of the group.

For each group, there is one Group Moderator. The group moderator may control membership to the group by adding and removing members. They may also control the Group Type.

Open - All users may see the group and group members. Users may request membership to this group.

Closed - All users may see the group and group members. Users may not request membership to the group, but may be added by the group moderator.

Hidden - The group and its members are not visible to normal users. Users may be added by the group moderator. If a hidden group is a moderator of a forum, the group will show up in the Moderators list.