Eric Sink, the founder of SourceGear, provides an excellent set of articles on the fundamentals of using source control. Quoting from his introduction:
Our universities often don't teach people how to do source control. We graduate with Computer Science degrees. We know more than we'll ever need to know about discrete math, artificial intelligence and the design of virtual memory systems. But many of us enter the workforce with no knowledge of how to use any of the basic tools of software development, including bug-tracking, unit testing, code coverage, source control, or even IDEs.
Our employers don't teach people how to do source control. In fact, many employers provide their developers with no training at all.
I've certainly seen this to be the case with a number of my clients. Eric's HOWTO should be required reading for any developer, even if you work as a team of one.