It's a matter of Script

http://www.rit.edu/~txswml/rit737/finalproj/index.htm---Image rollover and dropdown menu. For rollovers the emphasis was on the photoshop while the dropdown menu was essentially styling combination of unordered lists within definition lists and use of javascript functions. The most painful part was trying to figure out how to make the dropdown stay in place and not effect elements around. Absolute positioning, taking the layer out of context of the document, was the solution. The only other thing to do is to code for when mouse event ends as the rollovers remain stationary.

http://people.rit.edu/~txswml/phpfun/
--- this form consists essentially of three scripts. The first to send information to the email address. The second to check whether required fields have been filled in and displaying appropriate messages on if the item has been sent/ or not. And the last was to make the form "sticky"-- if there is item of information missing the form will not reset and keep users' content and allow to fill in areas missing. The code has been implemented from PHP Solutions