cut door in house

IN BL 2.5 how do make an open door in a cube .
I just want to cut out a rectangle on 1 side of a cube.
I tried sub divide and remove vertices or ctrl-click and F key but the lines crooked.

use a boolean modifier

ok I am going to need more information as i tried adding a plane to the cube face and removing it but I couldnt fit the plane on the cube face

It may be useful to attach your blend file to your post (the the ‘Go Advanced’ option when writing a post and attach with the paperclip icon) so users can see your model and what you are exactly working with.