How do you log onto a test realm on World of Warcraft

How to login to a test realm well you go to the wow launcher and you have to look at the notes on http://www.worldofwarcraft.com/index.xml and should say right there and if it says that public test realm is open you press public realm on wow launcher you click public test and it will ask you to download the ptr thing and you will have a choice to copy a pre made character max level with complete raid gear and all that or you can copy one of your own characters and once its downloaded you click on the ptr and you get to test the realm and see all the new features