HOW TO INSTALL ADDONS

First, download your chosen addon to somewhere you can find it easily (I tend to use my desktop). That is, when given the choice of 'open' or 'save' choose 'save' and your desktop as the destination.

Once the download is complete, you need to unzip the file. WinZip is the most popular application for doing this - if you don't have it, you can find a trial version here

The destination folder (the one into which you need to unzip the files) is usually C:\program files\world of warcraft\interface\addons

Once unzipped, re-start World of Warcraft. When you get to the login screen (where you select which character to play) you will see a red and gold button at the bottom left, labelled 'Addons'. Click this, and on the following screen activate the addon.

Return to your login screen and login as usual. Voila! Your addon should be installed!