Hello and welcome.
The best tip I can offer you on learning Photoshop is to find and follow as many tutorials as possible (not to mention just "playing" with it - open an image then click on everything to see what it does).
Here at BioRust, you can find some nice tutorials as well as a long, looong list of other sites that offer tutorials. They're easy enough to find. (the list is in the forums).
If you're set-up and capable to download and watch Quicktime videos, you should check out Dr. Brown's videos -
http://www.russellbrown.com/tips_tech.html - he's a strange one, but his tips are top notch.
Another good set of videos is called PhotoshopTV by those guys at NAPP. You can find them at iTunes or download them directly from their website -
http://www.photoshoptv.com/
Good luck.