Wireless network adapters do not come standard on Dell computers.   If you did not order a wireless network adapter with the system or did not install one later, then you do not have one.  The 4700 does, however, have a built in ethernet network adapter (this is the network interface card).  You can connect to the router through a wired ethernet connection to one of the LAN ports on the router.  If you want it to be wireless, you will have to purchase and install either a PCI wireless network adatper (preferred) or a USB wireless network adapter (less reliable).

Steve