Push Pull tool only works with simple shapes

I did follow the instructions but am starting from a different logic. My program doesn’t blow away a whole section just by highlighting. Anyway forget the explanation.
Hint: don’t do your plan on the roof using numbers and then add the sides as it won’t pan or rotate on the right plane. Awkward.
Secondly, I’ve got the faces from a rectangle actually working to my numbers. But…
brokensides fix it.skp (285.5 KB)
I have to now add the triangular section as in diagrama
I’m afraid my skills are not as smooth as need be for the full gazebo yet.
Can I when done attach a skp file to the house skp?