1.) Exit "World of Warcraft" completely

2.) Download the Mod

  Make a folder on your desktop called "My Mods"
  Save the .zip file to this folder.
  If, when you try to download the file, it automatically "opens" it... you need to RIGHT click on the link and
     choose "save as..." or "Save Target As".

3.) Extract the file - commonly known as 'unzipping'

* Windows Users
  Windows XP/Vista has a built in ZIP extractor. Double click on the file to open it, inside should be the file needed.
     Copy these outside to the "My Mods" folder.
  WinRAR: Right click the file, select "Extract Here"
  WinZip: You MUST make sure the option to "Use Folder Names" is CHECKED or it will just extract the files and
     not make the proper folders how the Author designed

* Mac Users
  StuffitExpander: Double click the archive to extract it to a folder in the current directory.

4.) Verify your WoW Installation Path

That is where you are running WoW from and THAT is where you need to install your Mods.

5.) Move to the Addon folder

  Open your World of Warcraft folder. (default is C:\Program Files\World of Warcraft\)
  Go into the "Interface" folder.
  Go into the "AddOns" folder.
  In a new window, open the "My Mods" folder.
  The "My Mods" folder should have the "ReagentID" folder in it.
  Move the "ReagentID" folder into the "AddOns" folder

Don't open the "Reagent ID" folder itself to copy the contain as some needed files will not be copied this way !

6.) Start World of Warcraft

7.) Make sure the AddOn is installed

  Log in
  At the Character Select screen, look in lower left corner for the "Addons" button.
  If button is there: make sure all the mods you installed are listed.
  If the button is NOT there: means you did not install the AddOn properly. Try repeating the steps or getting someone
     who knows more about computers than you todo help.