Probably the best thing to do is to try it without the webcam and see what the quality is like (i.e. doing voice calls). If this is okay, then get a webcam and try that out.
You can download Skype from:
www.skype.com
The user guides are [broken link removed].
The other person you are trying to call will need to have Skype aswell. You will both need webcams if you both want to see each other. You will both need broadband connections.
Adding a webcam is *relatively* simple! It's worth buying a slightly more expensive one (a low-end logitech one for example) if you are unfamiliar with computers, as I bought a cheapo one recently and the instructions were in the most bizarre chinglish! You will need to install the driver for the webcam and then connect the webcam to a USB port. Skype should (never seen it not) pick up the existence of the webcam automatically.
I use Skype between Ireland and Indonesia regularly and it works well. Sometimes the connection is not great at the Indonesian end, so we can only do voice calls, but mostly it works well and you get used to the occasional freeze and delay. In fact, my children (4 & 2) are better at coping with it than I am!
(I have no connection with Skype, other than as a user).
(Edit: I knew Clubman was a quicker typer!).