Samsung ML-2251NP - Manual (Page 185)

I NSTALLING P RINTER O PTIONS
E.8
5 Unfasten the antenna connected on your wireless network
interface card and insert it to the corresponding slot of the
machine.
6 Make sure that the connector on the card is properly placed
on the connector of the board. Push the card firmly.
7 Fasten the two supplied screws.