What I want to do is make my roll-over menu to be as a separate file so when I make any changes to it, it automatically updates the other pages without me having to update every single page individually. Any ideas on how to do that? Many thanks!!
If you're using Apache as your web server you could use server side includes:
Alternatively use a server side programming language to 'include' the menu in every page served.
brief intro to PHP include():