Step 1: Locate Your World of Warcraft Interface Folder

• Right click on your WoW launch/shortcut icon on your desktop or in your start menu and select "Properties".
• Click the "Open File Location" button and it will open the your WoW installation folder.
• Double click on the "Interface" folder.

Step 2: Unzip Your Addon Folder

• Unzipping your .zip file may vary from machine to machine, but double-clicking the .zip file or right-clicking the .zip file and selecting "Extract All..." should work.

Step 3: Move the Addon Folder to Your World of Warcraft Interface Folder

• Move the addon folder into the interface folder you opened in Step 1.

Step 4: Make Sure the Addon is Loaded

• At your character selection screen, after you select your character but BEFORE you hit the "Enter World" button, click on the "Addons" button in the lower left corner.
• Make sure that the box next to the addon's name is checked, and that you have the "Load out of date AddOns" button checked in the upper right hand corner.