If you are brand new to Photoshop, start here: How to Get Started with Photoshop CS6
https://www.youtube.com/user/pstutorialsws
http://www.digitalartsonline.co.uk/features/illustration/50-best-photoshop-tutorials/
http://www.photoshopessentials.com/
http://www.photoshoptutorials.ws/
http://design.tutsplus.com/articles/50-great-photoshop-tutorials-for-clever-beginners–psd-785