Inputting Multiple Search Fields into Query String?

hey guys and gals

quick question…i am building a little widget that allows a user to type in keyword(s) into one input field and then a zip code into another

when the user clicks submit, it plugs them into the search url

i have it working for one input field, but i am not sure how to append the script for the second field…what would i need to change to the below script to add a second field into that query string?

btn.onRelease = function(){

any help is much appreciated…thanks for your time!