Ok down to business.This tutorial may introduce some new concepts, but don't get lost. Its is designed to be super easy!
1. New layer. Make a basic line like this.
2. Extend your line both ways.
3. Take the line layer and duplicate it. Take the dup. layer and go to Edit>Transform>Flip Horizontal. Position the 2nd layer such that the joining area is 3px long.
4. Merge your layers and duplicate the newly merged layer. Flip it Vertically. Position it below the 1st layer, something close to as I have done.
5. At the edges make a line like this. It should be on the outside of the 2px block.
6. Select gray colors for this 1st coloring. (I change colors a few times so don't get lost!) Use a light color for the wall facing the light source, a dark one for the far wall, and a middle color for the roof. Don't worry about getting perfect colors as yet.
7. Ok here I have added a sloped roof and a door. Make new layers for both and al additions to your house. Use a similar style as i have for the roof. The door is sort flat here, feel free to thicken yours. Use similar lighting principals for the inside.
8. We want the roof to overshadow the house so extend it as so.
9. Fill in the roof and erase the "garbage" lines.
10. I have switched to a pretty red color here, suitable for a nice little suburban house. The door has been rotated too; just select the door layer and hit Flip Horizontal.
11. Add some windows here.
12. Create a shadow like mine, and cut it off so part is on the wall, the rest on the floor.
That's it! I hope you enjoyed this tutorial and learned something from it.
