Electric guitar...

My aunt in Florida has the guitar she got with her 2006 beetle... When I visit her I want to check it out and try and play it. I already sent her a $50 amp from amazon. I'm wondering how I'll hook it up as I believe it may have a smaller hookup on one end of the cord to hook into the car?? . I know it talks about a 9-volt battery that has some kind of booster or something...