If you have the time, make sure you watch this! I know its long but, simply put, it has almost everything you need to know to start editing photos in photoshop. Scott Kelby is a Photoshop God as far as I am concerned! and a lot of photographers agree. You learn really neat tricks and get all the basics that you need to start editing photos. This video was filmed at a B&H event (Great Online Shop by the way! Love them!) check it out and happy editing!
Trey is one my favourite photographers and influencers in HDR Photography, I chose to share this video because I also get this question a lot and its an essential tool that you will almost always use in your post processing work. You can check out more of Tery’s work on Stuck In Customs and check out more of his tutorials at his Tutorial section.