From my point of view, you don't have to know php to work in the template files. If you know html and CSS, you will likely be able to help him, as long as you understand "the loop" and the templates tags.
Log in the account via ftp
browse to the wordpress install directory (in this case, I would guess it's beta/)
There, you will have a folder "wp-content". This is where you will find all the "content" stuff of wordpress (plugins, theme, etc.)
The theme your friend uses seems to be named "clean"... So :
There you will find the "template files".
Try to understand the template hierarchy first :
To get you started, normally, all "page" share the same header (header.php) and footer (footer.php) and have a "sidebar" (sidebar.php)
All other files are "between" these two files (index.php, single.php, etc.)
And the styling of all these files is in style.css...