You can get the file psiphon3.exe from the link above. The file has been checked by our antivirus program but we advise you to check it with you own solution or try free Panda Free Antivirus.
Download the 7.1 MB and start the installation by double-clicking on the file and following the steps of the setup process.
You won't face problems with uninstalling the program. Click Start and then Control Panel. Choose Psiphon and press Uninstall.