In this step, we'll assign brick as the material for the floor.
1. To access the floor, hold Ctrl, and middle click on the air part.
2. Select the floor part by left clicking on it.
3. Click Edit from the Materials context panel:
4. On the Materials quick edit dialog, select the material type:
5. From the Name menu, select Brick.
6. Click Apply.
What it should look like...
7. To verify that the Brick material is properly assigned, check the Design Study Bar and the part coloring: