Look to your left on the screen after opening this page.
<<<<<<< over there to the left, click on HELP(in blue)
Then scroll down to GET THE APP (in green) and click on it.
This will download and install the game onto your computer.
It will be called (something like) WGTLauncher and will be in your downloaded files.
Go to your downloaded files and open it.
I made a shortcut to WGTLauncher onto my desktop so it is easier to find.
Then each time you want to play, just click onto WGTLauncher and it will be there within 3 seconds or so ready for you to play.