ok i download the client from the link i get were it says PC or MAC then it goes to the blizzard download then what do i do?..like on the last one i had a WoWtest folder but i cant find the test folder this time how or what do i do to get the WoWtest folder to come up in my WoW folder .... the file size is 79.2mb
it says i have an older version 2.0.0.6080. and i need 2.1.3.6898. i thought that was the client that i downloaded

Okay, first thing you must do is Get up-to-date with the Most Current Live patch (2.2.0.7272 at this time)
Just sign into WoW The regular way, and the download should take care of itself.

Go to the site and Download the NEW PTR Client (You won't be able to find the old one). Make sure you make note of where it is. Once you've run the Blizz-Downloader, the download will usually go to a Sub-directory of the WoW Folder. Look for one that includes the Current Patch and the Patch you want to test.
Just run that mother, and you should be well on your Way!