This is just a quick and easy tutorial I made just now to help Jessy. Hope it is useful!
First thing to know about basements: they will allow window placement and let light in from those windows if the foundation is at least seven clicks high. I tend to favour 8 clicks high foundations myself, but with this tutorial, we will be doing one that is seven clicks high.
Another thing to know: foundation walls will not let you place windows or decoration items on them. It is better to build your basement with regular walls, then add foundation around it in order to deal with this problem.