You're confusing me a little bit, but I suspect I haven't been clear with my original question
The pages I am firing my user input onto are already written, so all I need to do is pass my search input to those pages.
EXAMPLE:
A user enters the name of an animal, and then chooses the dropdown "dogs" cats" or "rabbits". Depending on which is chosen, the user input is POSTed to either dogs.php, cats.php or rabbits.php.
Each of those php files is already coded to search the relevant databases from the site I am getting them from (this is probably the bit that sounds weird).
All I need is a way to make sure that you can choose which php page gets the search input fired off to.