Depending on your device, the way to install a beta version is different.
Windows / Mac
Open the file you've just downloaded (.exe or .dmg) and install the software as a normal application.
On Windows, you need to change the default installation folder if you want to keep your existing KaraFun software.
On Mac, you'll just have to rename the app before moving it to your apps folder (like KaraFun beta).
On Android, you'll need to install the APK on your phone or tablet.
Have a look here if you need help to do that.
iPhone / iPad
An iOS beta version is not available at the moment. Should you wish to be contacted when one becomes available, please get in touch with our Customer Care Team.