347210 Tree Style PHP Navigation

I have a page which requires a tree style navigation. Essentially I have a menu of course categories (pulled for the category table), displayed as a simple list. (you can see it here [login to view URL]) I also have another table entitled course, which includes many rows (shown here - [login to view URL]). These two tables are linked by category. A course can have three possible categories assigned to it. When the category title is clicked in the left hand menu, I need the page to refresh , and a sub menu appear underneath the category, listing the courses that have that particular category assigned to it. Each course will be a link through to the second page I provided above, displaying the course in full. I can supply existing files, ftp access and database schema. For security reasons however I can not give access to the PHP Admin direct. But this should not be nescesary.