Young teacher

I’m 28, but most of my students think I’m much younger. This has made teaching middle school much harder for me. Students curse right to my face. Back talk SO much when I ask them to do work. They didn’t start barely listening to me until I started sending them to in school detention. I have some students say they get irritated with their classmates because I let them get away with more than other teachers do and they treat me worse. Next semester I get all new students. Please give me some advice on how to get them to respect me from the start.