Please follow the below steps:
1) You would need to have firefox on your machine, if you don't have one you can download and install it for free from here
2) Install the GreasyMonkey addon from here
3) Download this script
Once the script is downloaded in your desktop, minimize the Firefox window, drag and drop the script (which has been saved on desktop), on to the minimized window and wait for 2-3 seconds. The script would automatically show up the installation window.