Having bought my Pi, added a PiFace, and got the emulator running, (there's a lot of useful information at PiFace – Guides) I now want to 'do something - i.e physically hook something up to see something happen! being a bit of a beginner at electronics I thought I would start with something simple - turning an LED on or off.
The first step is to assemble the components, and then make the LED turn and off using the PiFace emulator. Component wise I needed an LED, a resistor, some jumper cables and a breadboard. (A breadboard is a matrix which allows you to assemble components without soldering, for prototyping/designing) It was quite hard to get my head round what I needed to do - this is all completely new to me - but I realised that I needed to supply power to the LED and then turn it on and off by completing/breaking the circuit.
I found a really good guide here as a starting point which showed me how to hook up an LED to a Pi (without the PiFace connected) and to get an LED to turn on.
The circuit is quite simple - 3.3v supply from the Pi, a resistor in line between the supply and the LED, and then a return to the IO port which will control switching the LED on and off. The photo below shows it hooked up on my desk.
Here's a close up of the bread board wiring
And that's it - you can use the emulator to try turning it on or off, or write a program to do it. I've written a java program using the Pi4j extension - and you can see the video of it running here.