How to use this Toggle Switch?
It's basically a push button. Possible examples depend on what you want to do. As it seems, you simply want to start interfacing it with Arduino, just use it as a normal push button. Use the DigitalInputPullup example, that comes with the Arduino IDE:

Middle pin to pin 2 on the Arduino
One of the other pins to ground (depending on which state you want to be reflected with a HIGH in the Arduino)
The other pin unconnected


Look at these two schematics. The left one is a normal push button. It connects, when pressed and disconnects, when released. The right one is your button. When pressed it disconnects the upper  pin and connects to the lower pin. When released vice versa.  When you don't use the upper pin, your button behaves just like the push button on the left.







simulate this circuit &ndash; Schematic created using CircuitLab