If you haven't got Winrar, then click
here to download it.
It's free, and you're going to need it.
Now that OptimumPT is downloaded, you'll need to right click it, and extract it to
Local Disk(C:) in your computer.
Extracting
Go into the folder which you've downloaded OptimumPT.
You will see a file that looks like this:

Right click that file, and you will see a list of actions, select the one the arrow is pointing to. "Extract Files..."
Now create a folder in Local Disk(C:) and name it "OptimumPT". This is very important.
Local Disk(C:), Just like I said!