@b0rk otherwise, my general tactic, and what I recommend to lots of people who want to learn computers: get a burner laptop for like $100. Learn how to wipe it and start over. Then go wild. If there's no valuable data on it, it doesn't really matter what you do with it.
E.g. this is how I test backup software, because I don't want to hand my "real" data over until I think I can trust one.
People need playgrounds. Their sole machine with their entire life's worth of data is not a playground.
@groxx did you use this playground approach yourself? did it help? what kinds of stuff did you do on your playground computer?