The script mentioned in the darrenjw's answer downloads a pre-compiled module based on your kernel version. It's quite likely that one of these modules will work for you though you might have to search through the script to find the right module. The lastest one worked for me, I'd start by downloading and trying that.
tar xfv 8192cu-20120701.tar.gz
sudo mv 8192cu.ko /lib/modules/3.1.9+/kernel/drivers/net/wireless/
sudo insmod /lib/modules/3.1.9+/kernel/drivers/net/wireless/8192cu.ko
If you then enter
iwconfig and are presented with a list containing
wlan0 then the module was successfully loaded. If none of the pre-compiled modules work then you may have to build your own, however, this isn't as simple as it should be.
Once you have the module loaded you will need to configure your network. Start by setting up the interface:
sudo nano /etc/network/interfaces
and add the below text to the end of the file:
iface wlan0 inet dhcp
sudo nano /etc/wpa.conf
and add the below text replacing NETWORK_SSID with your network name and NETWORK_PASSWORD with your password:
Secure the file with:
sudo chmod 600 /etc/wpa.conf
sudo ifup wlan0 and you should be connected.