The absolute best book for Photoshop is 'How to Cheat in Photoshop' by Steve Caplin, which is mainly about compositing photomontages. The 'You Suck at Photoshop' series is also excellent.
In general, books aren't the best way to learn graphic-design software. Your best bet is to sign up for a class, find someone who's very good at it to teach you, or just grab a copy and practice your ass off. If you can afford a legitimate copy of Photoshop or 3ds Max, you should be able to get a class!
Project Manager/Designer - Team Stevens - Game Development<br>
Engineering Management Trainee, Stevens Institute of Technology