If you have some kind of piano and keyboard around, try to memorize and play different scales (start with major/minor/pentatonic blues, later try modal scales as well), try to find out which chords can be created from their tonal material (apart from the blues scale where the chords are not necessarily formed from just the tonal material of the scale), and just improvise a little. You will be able to learn a lot by yourself.
If you do not have any kind of piano or keyboard around, get one.
Good to hear from you again in this thread, pauldrach. We last encountered each other in the John Cage 4'33 thread -- remember?
I think pauldrach's advice about using the keyboard to learn music theory as he's explained it in his post is an absolutely great
idea. Now that I think back to my days in elementary and junior high school, this is how I
learned a lot
about chords and harmony. (I also had my parents buy me a book which detailed each kind of chord in every key -- and I learned virtually all of them.)
It was also during those years that I started to play my favorite songs -- and TV and movie themes, too -- playing the chords I learned with my left hand, and the melody I picked up by ear with my right hand
As far as getting your own keyboard if you don't have one, these days, buying a piano -- even a used one -- can be an economic challenge. However, there is a page that I helped set up as an Amazon.com affiliate which provides a few different links for economical electronic keyboards, ranging in price from about $100 to about $200.
I think those are pretty good prices for what you get, so if you're interested here's the link: http://bit.ly/amazon_keyboards