This tutorial will teach you the basics on how to turn your mesh into an space station module for Orbiter, using Vinka's Spacecraft2.DLL
Notice that Vinka has made several versions of Spacecraft (Spaceraft.dll, Spacecraft2.dll, Spacecraft3.DLL) and some patch for the latest Orbiter 2006 P1 version.
The spacecraft.dll series allows you to make a flyable mesh without coding DLL modules in C++.
It was updated to work with Mesh Wizard, an application that can be dowloaded here at OrbitHangar.