You may watch a demonstration video showing the instructions that are detailed below - in HTML or in Direct format.
The first thing you should try is try pressing the "Start" button, and then clicking on the "Get New Module" button and choosing "Oscillator module". This, when done, should give you a nice boring 440Hz tone (quite similar to a US dial-tone). Try adjusting the slider directly under the words "Frequency control". This will allow you to control the frequency of the oscillation... pretty simple really.
Now a word or two about the control data and control sources... That frequency slider, just as many of the other sliders on the modules in RolloSONIC control some part of the synthesis... some setting. Notice the words "Frequency control"; It says that because the drop-down box directly above it lets you choose what kind of control there should be for this setting... in this case, the frequency setting. Settings with a drop-down of this sort can often be controlled manually (as is the default for most of the options), or they can be controlled via a control source. A control source can be any of the "Control..." modules or any of the available 14 mouse movement based parameters. Try, for fun, to set the Frequency control to "Speed", which is the speed at which the mouse is currently travelling. This will cause the frequency to wind up when the mouse is moved quickly, and then of course wind back down as the mouse slows down.
If you have a MIDI keyboard attached to your system, you may want to try creating a configuration with two new modules... An oscillator module and also a "MIDI-input module". When you do this, be sure to set the "Frequency control" to the name of the MIDI-input module, which will of course need to have been created already to show up in the list. Then, be sure to choose the correct MIDI-input device under the drop-down labeled "Input-device". With this simple configuration, you should be able to play up to 128 notes of polyphony through the oscillator. All notes, concurrent and otherwise will be affected by the settings of the oscillator module.