A warning light has come on in my S reg Vauxhall Corsa?

I have an S reg Vauxhall Corsa and a warning light has come on in the dashboard that I don't know what it means. It is on the rev counter dial and looks like a picture of a red man with a seatbelt on with a ball infront of him. I think it may be related to the airbag but how do I get it to go? My dad was playing around with the stereo because I had my cd palyer nicked and he was trying to fit the original radio back in but couldn't attach the wires at the back so I wasn't sure if the airbag had somehow got knocked in the process?