Video: Synth Basics - Episode 1
This two-part instructional video covers the basics of subtractive synths. It contains an overview of the different controls and what they do.
This video covers basic synth modules including the oscillator, filters, and envelopes, their controls and how to manipulate them to create a wide variety of synth sounds. These two videos will give you a good overview that carries over to all subtractive synths - both hardware and software. In this case I'm using the Subtractor synth in Reason, but the theory applies to all of synths.