Hi Mary
The way you do this is by creating folders in the Project Manager, then either create new topics inside the folders or move existing topics into the folders.
If you are working exclusively in the Project Manager, you are only able to move a single topic at a time. If you want to move a swarm of topics, open the Topic List pod and you are able to select as many as you want. Then drag the selected topics to the folder over in the Project Manager pod. Be a bit careful when dragging. Often, the mouse will pass over a tab at the bottom of the pod and it may change views on you.
Cheers... Rick 