1. Download OrbiterSDK, install and READ ALL of the documentation (3 documents).
2. Go to Harmsway's site and check out the tutorials he has listed. If you don't know where Harmsway's site is, go here:
http://simcosmos.planetaclix.pt/first. At Simcosmos site you will find links to most of Orbiter's resources.
3. Scan through the OrbiterSDK forum at the m6 forums (these are the main Orbiter forums, links from the Orbiter website if
you need them).
With the software you have you pretty well have everything you need to design the ships. The one thing you are missing is the
Max to Msh exporter to get your ship into Orbiters msh format. When you hit Simcosmos site, you will find it in the Tools
section, or look for Mindblast's site.
That just gets you the ship. Functionality is a different matter but there are a couple of ways to go. You will see this as
you explore the points above. Go on a trip and explore. Feel free to ask questions as you go ... but do read the documentation.