Really effective cardio treadmill routine?

I’m gonna start going to the gym again! But I really need an effective cardio treadmill routine that focuses on stamina. I took a dance class the other day and struggled with keeping up, I got tired out so fast. Never happens but it’s because I haven’t been physical that much over winter. I don’t really know anything about gym so please help with tips! I also wanna get toned, I’m naturally extremely thin like a stick and wanna put on muscle but don’t know where to start! No mean comments :)