How do I add zip codes to quick search

I would like to add a "within X miles of zip code" option to my quick search box but I can't figure out how. Can anyone tell me how to do this? I have installed the zip code download and have also made an advanced search area but I'm unable to change anything in the quick search.

there are duplicate functions

ones in inc/design.inc.php

the real function resides in templates/base/scriptsbxbaseindex.php

function quicksearch

you can make your edits there.

Thanks for the  info. However, once I am in scriptsbxbaseindex.php and I've found the fuction quicksearch area, what code do I write in? I want to add: search by Couple or Single, Location, Keyword and predefined list I've made (thru the Admin Panel). Can I just copy and paste code from the search.php file? What exactly would I copy from that? I've spend two days trying to figure this as it's something I reallly need on my homepage. Your help would be greatly appreicated!