insert data into a form mailer from another page
I have a form mailer on my site for booking tours, currently the user selects a tour from a drop down list.
If the user gets to the booking page from a page which provides information on a specific tour, i'd like that tour to automatically appear in place of the drop down list.
(eg, you've decided you want to do a 3 day Ayers Rock tour, so you "click book this tour" you are then taken to a booking page, I don't want you to have to select that tour again from a drop down list, I'd like this tour to appear in place of the drop down list.)
Essentially I need to get the data (tour name) from the first page, and then insert it in the form mailer on the booking page.
If someone knows a website where I could learn how to do this, or even tell me what this process is called, I'd be more than grateful.