Select this link to download the most recent version, Redhaven Outline Setup 3.3.1.
Save it to your hard drive, then find it, open it, and run the setup file that it contains.
If you are installing this program for the first time, just run the setup program and follow the instructions.
If you are updating the program from a previous version, make sure Redhaven Outline is closed, then just run the setup program and follow the instructions. It will automatically detect the previous version and update it without changing any of your settings or disturbing any of your outline files.