If you don't do so well by learning online, I reccomend purchasing this book to be used with Adobe CS5:
"Adobe Photoshop CS5 Classroom In A Book" - ~$20
I used it in college and it was very direct and to the point. You will learn how to use various tools including the selection tool, most brightness/contrast techniques for photo editing, how to use some advanced CS5 features and more.
Now it won't tell you how to design things, only teach you the program. There's a large difference between actually learning how to design and how to learn a program.