SoftKeys is a home screen replacement and on screen service that provides virtual buttons for home, menu, back, and search. In order to use SoftKeys you must have a working SuperUser installation on your device.
The first time you run SoftKeys from the "home" button, it may look like nothing happens because the default configuration is to pass you through to your configured home screen. If you've never configured SoftKeys, this will simply be the first one it finds on the device. To open the SoftKeys home button interface, you will need to "double tap" the hardware home button. This behaviour can be changed in the settings.
If you are using SoftKeys for the first time you should double-tap home, press the Settings button, and set your default home screen under Virtual Home Button - Normal Press
If you just want to just use the service and not the hardware home button behaviors, just set your default home to whatever launcher you like and then start SoftKeys from that launcher. The service can still run even if you don't make SoftKeys your default home application.