I need help

how do I install a texture pack (resource pack) using WinRAR I don't understand to do it and I haven't seen a video I don't want a video on how to put it in I know that I want to know how to change the file to a format that will work because when I put a texture pack in after downloading nothing shows up so I want to know how to change the file into the right format
(I am on windows 8 if it makes a difference) thanks