Before you can install and Twhirl, you need to install Adobe AIR on your computer.
After you have installed Adobe AIR, download the latest version of Twhirl to your deskop. You will be able to start the installation directly by double-clicking on the downloaded file.
If nothing happens when you double-click, there’s another way to install .air files. Go to Applications -> Accessories -> Adobe AIR Application Installer. When it’s open browse to the desktop (or wherever your twirl installation file is), select the file and click OK (see pic below). The installation will now begin.
Once the installation has finished, a shortcut to Twhirl will be automatically placed on your desktop. You can also find Twhirl in Applications ->Accessories