I have a job interview How do I get the job?

I have a job interview at Macy's on June 24th. Im going crazy because I really want this job. Im use to working at fast food places and supermarkets and things of the sort so I dnt know how Im susposed to dress, talk, and act. I also want to ask when they say do you have any questions for me what am I susposed to say? PLEASE HELP!