Hi pankeriste.

The easiest way without doing a UV map of the wall is simply to select the face you want to texture, go to edit polygons -> texture -> planar mapping (options box). In the options box, make sure that automatically fit the projection mainpulator is on, then check the appropriate mapping direction, then hit project. You can then simply grab the handles on the corners of the projection manipulators and squash/move the texture around to your liking.

Hope this helps :o)

LisaG