C1. I've installed Orbiter, how do I start?

Assuming you have configured the video and other options in the Orbiter Launchpad dialog, you are ready to take off. Pick a scenario from the list, and click the "ORBITER" button.
In a nutshell, the most important controls are on the numerical pad of your keyboard: Ctrl+ for increasing main thrust, Ctrl- for decreasing main thrust or engaging retros, Ins and Del for increasing/decreasing hovers (if available), and cursor keys for attitude controls. You should read the Orbiter manual in the Doc folder for a full list of keyboard functions, as well as explanations of the instrumentation.