Help with Plugin: User Photo

I am trying to figure out how to put a user photo on my post. I found User Photo as a Plugin and installed it.. I am not that familiar with code…I am not sure in which Template file to put the code…out of all these…
* 404 Template (404.php)
* Archives (archive.php)
* Comments (comments.php)
* Footer (footer.php)
* Header (header.php)
* Main Index Template (index.php)
* Page Template (page.php)
* Search Results (search.php)
* Sidebar (sidebar.php)
* Single Post (single.php)
* Theme Functions (functions.php)

Or is it the stylesheet (style.css)

Help please..and if anyone knows of any video tutorials on wordpress.org ..that would be great too!!
Thanks!!