How to construct a wall or room?

Question:  How to construct a Wall or Room

Answer:

1. Click "Sets > Room Builder "
2. Move the pointer back onto the grid, depress the mouse button and drag the pointer diagonally.  Red lines appear behind it, representing top-down views of the walls as they're drawn.  Simultaneously, numerical headers display the horizontal and/or vertical dimensions of the structure.
3. When the structure is the size and shape you desire, release the mouse button
4. Repeat as needed