How to pass data from a one form to another

[eluser]Linkark07[/eluser]
Hi there.

Sorry if the title is a little confusing.

Ok, here is my problem: I have a dropdown list with names of some courses from a table. The user should select one of them and then click submit.

After that, another form appears with textboxes that must be populated with more information of the course the user selected, let's say, duration and cost.

I have been thinking this since yesterday but nothing has come to my mind as to how solve this part.

Anyone could guide me as to how obtain the name of the dropdown list, use it as a where for my select query and then with the results populate those textboxes.

Thanks in advance!