Photoshop doesn't come with tutorials that I know of. I have "the official photoshop handbook" here at home, but honestly, I've never used it. If there is anything in particular you want to know, feel free to PM me for tips, I'd be happy to help if I can. (Or I could dust off my book and look it up for you)
a good place to start is to open a small photo, 72 dpi (screen resolution). Once you have that, start going through the tools to see what they do, then start going through the menus to see what they do, etc....
The reason I suggest a low res image to start with is for the filters, the larger the image, the longer it will take to process the filter (or effect).