Wireless connection

In my list of wireless networks my wireless network doesn't show up. Is my wireless network card off and how do I enable it?

System → Preferences → Hardware Information: The Hardware information item isn't visible in the menu.

sudo lshw -C network gives the following information:

  *-network
       description: Ethernet interface
       product: 88E8040 PCI-E Fast Ethernet Controller
       vendor: Marvell Technology Group Ltd.
       physical id: 0
       bus info: pci@0000:09:00.0
       logical name: eth0
       version: 12
       serial: 00:1d:09:5c:f3:c6
       size: 100MB/s
       capacity: 100MB/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=sky2 driverversion=1.20 duplex=full firmware=N/A ip=192.168.2.3 latency=0 link=yes module=sky2 multicast=yes port=twisted pair speed=100MB/s
  *-network
       description: Network controller
       product: BCM4312 802.11a/b/g
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci@0000:0b:00.0
       version: 01
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list
       configuration: driver=b43-pci-bridge latency=0 module=ssb
  *-network DISABLED
       description: Wireless interface
       physical id: 2
       logical name: wlan0
       serial: 00:1f:e1:3b:97:84
       capabilities: ethernet physical wireless
       configuration: broadcast=yes multicast=yes wireless=IEEE 802.11g