Okay im going to go step by step into this with you:
Click the programs tab
In name type in limewrire pro
MAKE SURE YOU HAVE A DAMN GOOD VIRUS PROTECTER!Because a lot of programs are wrapped in trojans. I have Symantic Corporate edition and it has saved me so many times
Look intill you see Limewire PRO! Not Limewire because that is what you already have. Most likely its going to be in a Zip file.
Download it, and wait.
Now when its done double click it it will open the zip. Unzip it and make sure your anti virus is on.
If its good then your anti virus wont say anything and you are free to install it as you would with any program.
Have fun Pirating!