There is a wall set and some window sets in free stuff. There is a tutorial also here on this site that shows how to do it in Poser. Basically you take a cube primative and scale it down so that it is 2D. Just a square. Then you save the square to your props library. Next you add several of these from your props library offsetting each. The free stuff is a lot better than you'll make yourself unless you have a 3D modeling application. Poser is great for animating and posing but isn't worth a dang as a modeler.