Okay! In "core" folder you have 3 other folders "common", "modules", and "templates". Inside "common" there is php file which will go to your "root/core/common" folder. Inside "modules" there is another folder called "WTHR" with a php file inside it, copy the whole folder to your "root/core/modules" folder. Finally, inside "templates" there is a folder called "wthr" with 2 php files inside it, copy the folder to your "root/lib/skins/(name of the skin you're using)" folder and you're done. Same procedure goes with all of my modules.