WEP Wireless encryption on a Dell Inspiron 15

Need to know how to set encryption for new Dell Inspiron 15 laptop. We have a Trendnet wireless router and used encryption code. Have wireless USB adaptor for three desktop PC’s and had no trouble at all getting them set up. At work we use Intel Pro wireless and I’m fine with that, but i’m not able to locate where to go on new laptop to type in encryption code. Called Dell a couple of times but we keep geting folks with very heavy accents that we just can’t understand. Laptop has a wireless n card. We are using a WEP key#1 128 bit encryption. Any help would be very much appreciated. Thanks!