Adding year, make, and model/trim drop down menu onto website

Want to see how I can add CarQuery's API for year, make and model/trim to my Squarespace website. Not really sure how to do this, but I'd like to be able to since it's vital to my website. I need this figured out like yesterday, and maybe my brain's functionality is at a zero because I got 10 millions things going on at once, but I could really use the help since I can't seem to figure it out.

it should be downloadable into squarespace but just don't know how to do it.