If you want to learn photoshop.. here's what I would do.
First, invest in a pen tablet. go to http://www.wacom.com
you can pick the smallest tablet of the Intuos line. This
will magnify the power of photoshop 1000%.
Next, go to the bookstore, new or used and get the official
ADOBE: Classroom in a book, series.
Third, look at every tool and filter that photoshop has to
offer and see how it works. check out everything. Then begin
to learn how to use it for your needs.
Then, you can branch out to third-party books, web sites,
and magazines to pick up hundreds of tips and tricks.
In about three months, you can be somewhat competent with
Photoshop and Image Ready.
After that, study art till you want to puke. That is where
you learn to get the most from photoshop.