If you want to learn the basics of scratching, "Qbert's DIY" series of DVDs covers all the basics, and they've got nice tutorials. You can loop the DVD, change the angles, it's all really nice.
If you just want to know how to spin at a party or something, look up information on beatmatching and transitions, it's all relatively simple. Beyond that, knowing how to be a good DJ and rock a good set is solely a matter of experience. Knowing your crowd/knowing how to read a crowd are skills that only come from experience.