Hooking the airbags back up

You need to make sure that the airbag sensors you have are good first off, secondly there are 3 sensors and they should all be installed with the arrows facing forward(most manufacturers put arrows on them).
Make sure the battery is disconnected and has been for at least 30 seconds, but I like to wait more like 30 minutes before trying to hook the airbag system back up. There is an energy reserve module located on the car that holds power for the airbag system so it needs to be drained before hooking up the connections.
It would make me nervous hooking it up without knowing wether or not the sensors are good. This can be checked out by any good sized body shop. Also after you do this they may have to hook up a computer to your car and clear all the codes for the airbag system.

Take it to a shop and ask them to test the air bag sensors and get rid of the flashing light. It "should" be as easy as pushing a couple buttons and spending about 15 minutes on it.