unable to connect wifi from terminal

Question

I would like to connect WiFi from terminal. I followed this instruction.

Connect to WiFi network through Ubuntu terminal

Output looks like something is wrong.

What to do?

taro@taro-HP-Mini-110-3000:~$ iconfig wlan0
ipmiutil ver 2.97
iconfig ver 2.97 
Cannot map memory.
Cannot open an IPMI driver: /dev/imb, /dev/ipmi0, /dev/ipmi/0, 
     or direct driverless.
ipmiutil config, cannot open IPMI driver
taro@taro-HP-Mini-110-3000:~$ iwconfig wlan0 essid Free Westfield WiFi
Error for wireless request "Set ESSID" (8B1A) :
    SET failed on device wlan0 ; Operation not permitted.
taro@taro-HP-Mini-110-3000:~$ dhclient wlan0 
Cannot find device "wlan0"