If you're a Game Master, the blue "Manage Folders" button at the top of the main Family Trees screen lets you organize your trees into folders. Each folder becomes a tab on the main screen.

On the Manage Folders screen, click the green "New Folder" button to add one. Give it a Name, and optionally set the Secret? toggle to hide the folder from players. Use the green "Edit Folder" button in any row to rename it or change its secrecy.

You can drag folders by the grip handle to reorder them; the order saves as soon as you drop a row. To file a tree into a folder, choose it in the Family Tree Folder dropdown on the tree's edit form.

A couple of things worth knowing: marking a folder secret hides the folder and its contents from the main screen, but unless a tree inside is also marked secret, players may still reach it through a direct link or search. And deleting a folder never deletes the trees inside it — they simply become unsorted and move to the "Unsorted" tab.