Application form re-direct

To add or alter an existing php form script on my website,? so that when a customer selects a certain option from one of the drop-down boxes, the? customer will be re-directed to a relevant page within my site. eg if the customer selects 'i am a homeowner' they are sent to [login to view URL], but if they select 'i am not a homeowner' they are sent to moredetails.html.