Learning how to tilt buildings in photoshop is easily done.
Have a look at the tutorials on Lyzardstomp's website. It's not mapping but if you go through them, you will very quickly pick up how to create certain effects (rotation of objects being one of them). See in particular this tutorial for learning how to rotate.
I learnt more about how to use photoshop for drawing things (rather than manipulating photos) from this site than I have from any other.