these commands are to help us to know what your system thinks is installed (not necessarily to get you connected).
lspci # will tell us the pci devices you have in your system.
lsusb # will tell us the usb devices you have in your system.
ifconfig # will tell us what network interface cards you have turned on in your system.
ifconfig -a # will tell us all the network interface cards you have in your system.
iwconfig # will tell us which of your network interface cards has wireless capability
now that we know that, this should get you connected:
sudo iwlist device scan # this will use the device interface (that from the above command, we found out has wireless capability) and scan for wireless routers that are accessible.
sudo iwconfig device essid "myssid" # assuming no security, use that device to connect to your router.
sudo dhclient # will attempt to get ip-address, subnet mask, dns server information automatically from your router assuming dhcp is turned on on your router.
as for a gui to handle this automatically in the future try these:
sudo apt-get install network-manager # to install network manager applet
sudo apt-get install wicd # to install wicd
also, make sure there isnt some switch or key combination to turn on/off the wireless radio.