You don't need PHP to do it, it is just pure HTML.
1) Give your frames a name.
<FRAME NAME='left' SRC='menu.html'>
<FRAME NAME='right' SRC='default.html'>
2) Give your anchors/hyperlinks a target
<A HREF='mypic.html' TARGET='right'>Show MyPic in right frame</A>
You can, of course, link to a PHP page:
<A HREF='process_pictures.php?pic_id=1' TARGET='right'>Load Pic 1</A>
You can also replace 'menu.html' with 'menu.php' which could setup the links according to a database.
EDIT: Put code inside (PHP)(/PHP) tags