My airbag light is on. I was told that there is some kind of sensor under the driver seat. Is this what causes the light to go on? I was told it could of gotting wet. Or can it be something else? If it is the on under the seat is it easy to change? Anyone else have this problem?

Chances are yes that'* the culprit...and could have gotten wet....
Easy to replce...probably fairly cheap to pick one up at a salvage yard.

I had a problem with the one uder the pass seat. it would only go on when someone sat there so if yours comes on when you/driver sits check to see if it came loose.
does anyone sit behind you (kids) and do they put there feet under your seat.

mine was loose.

There is a power connector (yellow signifies restraint system) under the seat. It supplies 12v+ to deploy the side air bag.