Simple Circuit Simulation tutorial
If you are on Windows I would download a copy of LTspice from Linear Technology. 
IIRC there is a tutorial in the download. If not it is on their website.

LTspice is very quick to get started with. A major advantage is that the package
comes with all of the semiconductor models for the LT parts. 
Most models are copyright and end up having to download them from the manufacturer.
This can be a major source of difficulty for people getting started.

Once you have the software I would start with a very simple circuit like a voltage
source in series with a resistor in series with a capacitor. Setup your
probes to plot the voltage across the capacitor and the voltage across the resistor.
This will enable you to learn the quirks of the tool and hopefully get some instant
gratification.

Make a copy of the simple circuit and start to add new elements to the new circuit.