Are several ways to create windows sscac3d ... depends on what you want.
1. Crudest form: use a texture for the wall that has doors and windows on it ... ok for distant objects not good in close ups
2. Slightly better : Cut a hole in wall, extrude edges of wall inwards then hilite inside vertices of extrusion and create convex object, texture it with a fancy windows texture. You can scale the inside vertices to be smaller (10% say) gives more 3d feel.
3. Better: cut hole, extrude edges, create rectangle to fit in hole ... now subdivide rectangle and then make hole in subdivisions ... get that lattice effect you want.
4. Best : look at Dennis's Haunted House ...
http://www.ac3d.org/forum/viewtopic.php?t=1346
See all the geometry additions he did
griff