how do I quit my job

I literally have been there only 2 weeks. When I went there I thought she would ask me after - days of training, but they never did. They just expect me to show up but I decided that I don't even want the job. I only work 2 days a week for 2 or 3 hours which is ridiculous. I dread going every time I have to because they literally make me work my butt off and I barely know what I'm supposed to be doing (since I've had only 1-2 hours all together on training) I just started but I don't know how to tell my  boss that. It's just not the job for me but I don't want to be rude and just leave. They have too many people already, I just need help, they next time I work is tomorrow. SOS