Game Masters can control the organization of their game's threads using Threadgroups. A game forum can have up to twenty threadgroups, and allows having a threadgroup inside a threadgroup, though only to one level (Game Forum -> Threadgroup -> Subthreadgroup).
Threadgroups can display, or appear to 'contain' threads, but the threads are not bound to the threadgroup but filtered by group. For example, a thread can be in several threadgroups at once, if desired. A threadgroup's contents will not display when looking at the threadgroup's parent (hierarchically). Threadgroups may be deleted and modified with no effect to actual threads, as they are only views or filters the thread just reverts to displaying in the main threadgroup. This allows for interesting and flexible light-weight thread organization.
The 'Main' threadgroup: Despite being under the 'Threadgroups' list, the Main threadgroup does not behave exactly like the others. You can not add threads to or remove threads from it, nor can you delete or rename it. It is the default display for your game forum. Any threads not in a threadgroup will show up here. A GM may edit options for it that specify from which additional threadgroups threads should be displayed by clicking the "edit" link next to the Main theadgroup.
To create a threadgroup: Click the 'New Threadgroup' link. Designate a title (alphanumeric, with spaces, underscores, single quotes, and colons allowed). If you wish this to be a top level threadgroup, choose 'No Parent.' Otherwise, choose the parent threadgroup accordingly.
To edit a threadgroup's name: Double click just to the right of the threadgroup name and it will transform into a field.
To delete a threadgroup: Mouse over the threadgroup row and click on the trash icon.
To add threads to a threadgroup: Select threads as per usual with the inline tools. There will be a select menu with a button to 'Add to' to its left. Select the threadgroup and the threads will be added to it. Note that if you are adding threads to a threadgroup that its parent already has, or you are adding threads to a parent threadgroup that the child already has, the threads will be removed from that threadgroup and added to the one you've selected.
To remove threads from a threadgroup: Select threads as per usual with the inline tools. Click the 'Remove' link next to the 'Add to' selection. This will not delete your threads.