How can I get into graphic design?

I see all these icons that people produce - for example Apple's icons - and I think to myself, why can't I make things like that?

Right now, I have a Dell Inspiron 17R. Not exactly the most powerful machine in the world, but it does the job. I also have an iPad 2. What I'm wondering is, are there any apps for either of these that are relatively inexpensive that I can use for graphic design?

Also, I need some tutorials in how to get started in graphic design. I have downloaded basic graphic design software in the past - for example GIMP - however I haven't really known where to get started. I'm sure some of you must be graphic designers, so do you have any tips and tutorials for me?

Thank you ever so much,