Click to open
In your Downloads folder, double-click the downloaded file. (The file name will begin with astir-desktop.) It will open the Ubuntu Software Center.
Install the app
Click the Install button to the left. You may need to enter the password you use to log in to Ubuntu.
Run Astir Web App
To run the app, search your computer for Astir Web App, and then double-click the Astir Web App icon.