Access only From A Certain Page

Hi guys,

I'm an absolute newb when it comes to things like this but heres an outline of what Im trying to do...

Ive got a really nice script that makes a user enter a username and password so they get redirected to a certain part of my site (their own client area) but im trying to prevent the user just typing the url into their browser to access it. I want them to have to log in every time they visit.

I understand this probably isn't the best way to go about it but someone told me if i use the .htaccess file I can prevent them doing this or at least only allow them to access a certain page if they are coming from a page that I set?

Any help would be great! Thanks!

Grey