Now I want to grow a little offshoot of my rectangle for the room on the right side of the house. I could select the rightmost face and extrude it to grow my house further to the right. However, if I do that, it grows the entire face, the entire right side of my house, which is too tall for my purposes. I also noted earlier that particular room is inset from the rest of the house's front:
What I'll want to do is strategically divide up that face, so I can pick just an appropriately sized section to extrude. One tool we can use is called ...