i will soon need to create a guestbook for a restaurant site that allows people to make comments about the service.
do i need to use PHP ? im totally lost as usual. any tutes out there ??

yes, you need some server side script like php or asp ......
to store comments from people, you need some database ..
to handle database, flash is not capable to do that, so you need php or asp or
some server script.............

I think this will works for you

http://www.flash-db.com/Tutorials/guestbook/