Welcome to the forum. I wish I could give you the help you're looking for, I'm over-committed as is. Learning Orbital Mechanics takes time, and I'm only available sporadically.
What I can offer is tips along the way. Learning Orbiter will require adjusting your view of "common sense" when it comes to physics. Start with a good tutorial, like "Go Play in Space". This is the one that most of us learned from. Read through the whole thing at least once, and expect most of it to be over your head. Then, as you follow indiviual sections in detail, and actually play Orbiter, you'll experience a series of "Ah-Ha" moments where the bits and pieces start to come together.
There are many people here who will be happy to help, but how much we can help depends on you. The more specific and detailed a question is, the more we can help. Make use of the forum search function, chances are you'll find an answer already exists. Xyon put together a good article on asking for help:
http://orbiter-forum.com/showthread.php?t=17071
Persistence Pays. You will fail. A lot. Then you will succeed at something, and feel elated. Then, if you are like me, you will fail utterly when you try to repeat it. Eventually, it sinks in.