I never know what to do at work?

I work at Jets Pizza, and while it's a nice environment, I feel so stupid at work every single day. Everyone else always seems busy and like they know what to do and when to do it, and I don't. When the phones aren't ringing I just kind of stand around and ask my coworkers if they want help with something. the only time I know what to do is when a manager tells me. what should I do?

Also, I can't make the pizzas, that's what the managers/older workers do.