2004 chevy cavalier airbag light?

Hello, i have a 2004 chevy cavalier 4 door base model and the airbag light is on.....i have read the code from the beeps as code number 51. Can anyone please give me further advice on what i can do for this, and does anyone know where the airbag control moduele is for this year of the cavalier. Thank you, i appreciate all your help