If you're downloading a file from a website or someone/whatever, put it into your templates folder.
If you have the code (like the example in the previous post), copy it, go ingame, press k, click the floppy disk thing, click template code, and paste it in the appropriate area.
Find the template code, copy and paste it into a .txt file. Save it in your template folder, which is found in your Guild Wars folder(in your My Documents folder on Vista machines, I think).
