Loading Plug Ins and Changing Templates

My first experience of WP was two days ago and I have no experience with code etc. I downloaded Tag Functions Plug-in. I then uploaded (using Coffee Cup) to my Plugins directory. I went back to WP to activate and when I refreshed I got a blank page ! I typed the URL in again and I got a blank page.
The instructions say to add some code to the templates, but this step is after activation. I looked for a directory or folder called Templates and cannot find one.Some assistance which leads me step by step in very plain language will be most appreciated.
Thank you
Lewis