Job

I’ve recently just got a part-time job at a local place. I’m 17 years old and it’s my first job. I only started today and have worked 12 hours already. I wasn’t allowed to take a break and i wasn’t allowed to even sit down. Tomorrow they want me to open and close myself when i’ve not even been showed how too. I don’t know if it’s worth sticking with the job or not because i’m unhappy and overworked already and it’s only my first shift. There has also been no talk about pay and whenever i bring it up the conversation changes. What should i do? Ps they want me to work 48 Hours a week over 4 days.