Find your rocket model
The first step in running Virtual Range, before you open the application, is to download a rocket model. Virtual Range can read the popular RockSim format, so you have access to models distributed by kit manufacturers plus many freely available in online libraries. The largest such collection is located at Essence's RockSim Library. Go to that web site and download a model for one of your rockets. Note which folder your web browser uses for file downloads.
Download an engine thrust curve
The second model you will need to simulate a rocket flight is the engine thrust curve. Virtual Range reads thrust curves in the wRASP format. These can be found online at ThrustCurve.org, among other sources. Pick an engine that is compatible with your rocket and download it.
Import files into Virtual Range
Now that your have your data files, start up Virtual Range by double-clicking on it. The first screen will show the only loaded rocket model, called "Demo". To add the rocket model that you downloaded, pull down the File menu, and select "Import rocket...". A file chooser will open, which you can use to navigate to your downloads directory and open your rocket model. After the file chooser is dismissed, the main screen will add a new button for your imported rocket. Select it. The next screen will show a list of engines that are compatible with your rocket model. Again, pull down the file menu and choose "Import engine...". Select your engine thrust curve and dismiss the dialog. After the engine appears in the list, select it. Your rocket will now be prepared for launch.
Fly
The main screen shows your rocket on the launch pad in the center, with buttons to the left and a flight status readout in the lower right. Click the red "Launch" button. If your engine is compatible and your rocket is stable, you will see it take off into the sky. While the rocket is in the air, a magnified view will appear in the upper right. You can put the rocket back on the launch pad at any time by clicking the "Reset" button. You can also change the parameters of the simulation by setting the wind speed, or choosing a different rocket or engine. When you are finished with your rocket simulation, you can quit the program by choosing the "Quit Virtual Range" from the "Virtual Range" menu.