Welcome aboard!
While you're already here don't hurt to read the entire tread from start. I have written several user manuals (outdated) but still valid.
0. All the awards have to go to Daniels118 and Emmanuel.

I know absolutely nothing about programming.

I'm not either.
1. Keep your hand and fingers safe; you will need them.
2. Be carefully, a dream could easy became a nightmare.
The last version is a nightmare for me and I'm a nightmare for Daniels118.
3. Nothing is perfect! (Not even God, look at the world created in seven days).
I've never tried round holes but half round. (See this post )
or Roof dormers tutorial .
If you need help just ask.