How to subtract 1 object from another? House

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?

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

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.