The command ifconfig wlan0 does not turn on your wireless card. It gives you information about your wlan0. To turn on your wireless card, you would enter ifconfig wlan0 up. Although, it’s not always wlan0. To find out the name of your wireless card, type iwconfig, and look at the row that has some information in it, not ‘no wireless extensions’.
To be able to run the commands ifconfig wlan0 up, iwconfig wlan0 essid WIFI_NETWORK_HERE key PASSWORD_HERE and dhclient wlan0, you need to be root. So, you have to put the word sudo before those commands (unless you’re already logged in as root).
The password in the command iwconfig wlan0 essid name key password should be in hexadecimal. If you want to type the ASCII password, you would use iwconfig wlan0 essid name key s:password.
The command iwconfig wlan0 essid name key password only works with access points that use WEP as encryption. If the access point uses WPA/WPA2, you’ll have to use another method to connect, found here: