In a couple of clicks, you can add an additional room to your plan.
There are two ways to add a new room to your plan:
1. Adding a room of a predefined form;
2. Using a drawing tool.
Tip: always create each room separately. Do not create one big space so you can add smaller rooms inside of it. That leads to layer conflicts and can cause you a headache in later stages. Create separate rooms and put them near the other.
Here's a short video that should help: