Using the program is as simple as clicking the refresh button, located in the upper right hand corner of the screen, and wait for it to find all the available networks. The process can take a good while depending on the amount of networks nearby that you have.
Once it has finished, you can select your network (it's important to not do this with networks that aren't yours, because you can be committing a crime), and test its security.
ReveLA WIFI is a tool that should not be used carelessly, because while it is easy to use and can help you with your own connection, the consequences of using it wrongly can be very bad. So, just as it is often said: use at your own risk.