How do I get ahead?

I've been wondering how I can move up in the company since I'm just a sales floor/cashier. The leads at my store do nothing but total work avoidance and pushthe work on someone else and it's really bad especially when I'm the only one willing to do the work. They all want to stand around at the cash register area despite the manager telling them to do otherwise.

There were 15 rails that was not done by day shift and sure as hell was not done by night shift. I had to do them all within 5 hours. These two idiot leads and decided they needed to cashiers and empty ass store where they spent the fucking night while I was working harder than anyone. I was seriously overwhelmed by the amount of work I was required to do by myself I could have gotten done within 2 hours with enough people working.

I contacted the store manager about this shit and she seems to not give a fuck or isn't telling me shit. They've been doing this for a long time and I think enough is enough I'm going to start regularly telling them every time they pull this shit. One of these leads were actually chosen over me. More than likely they have taken credit for the shit I've done.

I've been working there 6 months now. It's a time to leave?