Complaint Process For Dairy Queen Employee

I am a current Employee in South Dakota Dairy Queen. I would like to know the process to file a complaint for discrimination by other employees? Ive adressed this more then once with my supervisor and had no results and the the enployee I feel has an issue with my ethnicity and sexuality because she and two others have commented numerous times to me or other co workers about my ethnic background and my sexuality and that im not right meaning im screwed up because im half Asian and Native American also bisexual. Im 16 and feel like im a target for these three women to bully. When I've told my supervisor the owner he laughed and said they're silly old ladies and has not address anything other then no talking about politics as these women love to do and say out loudly that "all" immigrants should leave the United States and go home knowing my father is an immigrant from Vietnam. Before these women knew my sexuality they never bothered me but once they learned they make it a game to see if they can put me in tears. Ive been called uneducated and not right because im a half breed and feel that nothing will change. Ive worked with Dairy queen since i was 14 and appreciate the opportunity to give me a chance and get me into the work force but im saddened and ive given my two weeks notice. My supervisor means well and i believe he hasnt address this with the other em0loyees either he doesn't believe it or they worked with him so long, one ad long as 20 years, he feels he owes them. Im not the only employee this has happened to and id hate for it to continue because I wouldn't want young new employees deal with this and scar them from possibly fear working at all.