How to subtract 1 object from another? House

Support Modeling
1

I stopped working in Blender for a little while and have forgotten some of the important things.

I have a house(box shaped) that I want to make a round door in it so I created a sphere and extended it so I could use it to cut out a door shape out of the house. How do I use the sphere to cut out a piece of my house?

2

search Boolean, you can reach either in Modifier panel or press WKEY (in Object Mode).

3

better would be to delete the faces where the door will be, snap the cursor to those faces ( the ones remaining of that wall ), add a circle ( in edit mode ) then face the gap manually.