open a terminal and enter each command and press enter after each one.
iwconfig eth0 essid XXXXXXXXX X represents the name of your wireless network
ifconfig eth0 up
iwconfig eth0 key XXXXXXXXXXXXXXXXXXXX enter your wep key here
dhcpcd eth0
after the all are entered, enter iwconfig you should see output like this
eth0 IEEE 802.11-DS ESSID:"XXXXXXXXXX" Nickname:"Gab00n"
Mode:Managed Frequency:2.437GHz Access Point: 01:04:25:E6:6G
B
Bit Rate:11Mb/s Tx-Power=15 dBm Sensitivity:1/3
Retry limit:4 RTS thr
ff Fragment thr
ff
Encryption key:XXXXXXXXXXXXXXXXXXXXXXXXXX
Power Management
ff
Link Quality:55/92 Signal level:-42 dBm Noise level:-98 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:5819
Tx excessive retries:30 Invalid misc:0 Missed beacon:0
the command route or the command ifconfig will show you ip information if the above commands worked.