Hi,
A couple of hints:
The basic signal flow of the virus is as follows:
oscillators->filters->fx
Along the way there are envelopes and lfo' s which may affect (modulate) any parameter of the mentioned components.
If you want to develop some feeling for it, start with a simple init patch and dive into the oscillators. First get some feeling for basic waves like square, saw, sine, etc. After that see what the 64 spectral waves sound like and experiment a lot.
After that I suggest heading on to the filters, then envelopes, then lfo's, then fx and finally dive into the oscillator wavetables.
A good bit of basic info can be found on the soundonsound website. Search for "synth secrets" and you'll find a good deal of basic concepts.
Another way of learning is by decomposing an existing patch. Search for a simple patch (for example a bass) and see how various parameters have been set. Remove the effects, remove the modulations and see what is left of the original....Reverse engineer the hell out of it and after that, try to recreate the patch yourself from an init patch...see how far you get and improve
Feel free to ask
M.