There are also many excellent books out there. Photoshop Bible for example. If you go to a bookstore such as Barnes and Noble, or Borders, than you should find MANY books on Photoshop 7.
Personally though, I think that the help menu on Photoshop is enough. All you need to do is search for what you want...and sooner or later, you'll no everything there is to know (as you use the different features, you become accustomed to how Photoshop is layed out).