To add a room you will need to create a room type for the room to be assigned to first.
Once a room type has been added, you can add a new room to your room type by going to:
Settings > Rooms > Rooms and room types
Click on the dropdown to expand the room type
Select + Add rooms
Enter the room name
Click +Add another room if required
Then finalise by clicking +Add (x) rooms
Depending on the Preno plan you use, there may be a limit to the number of rooms you can have on your account. If you need more rooms, please get in touch with the support team.