Social Networking

Okay, I am so behind the times on this one. Everyone talks about myspace and facebook. Everyone in my family but me has a page on one or both of these. I actually signed up for one of them to keep track of my kids' doings on them, then delegated the task to my husband, since he routinely uses it, and I don't.
I guess my biggest thing is that I'm scared of identity theft, or weirdos showing up on the doorstep, thinking they know me because of my page. The articles say to make it private, but I'm not sure how that plays out--if it's private, then it's only people I invite in??? But one of the articles said that private doesn't really mean private--people can still access your information. And, if it's private, then how to I go about meeting people with similar interests? How much information can you give before you've crossed the line? If I say I live in Virginia, is that okay? What about Richmond? I have an unusual name, and I would be easy to track for anyone determined to do so--for that matter, for anyone who can use google. So, is it truly a big deal to post that on a page?
I have so many questions about this that it paralyzes me. It's easier not to do anything, then to do something and have people say, "Well, you should have known better..."