As discussed in the introduction, this tutorial will cover two basic parts. The first part is to generate the image of the moon that you want in your sky. There are a few basic quicky things to do.
1.) Open up a completely blank empty scene.
2.) Get rid of all the lights (we're going to put lights back in a few steps).
3.) Insert a sphere. Put it at 0,0,0 (X, Y, Z).
4.) Move the camera that you want for the final render camera to the position shown in the screen capture with the rotation shown.
Note on this step: A few versions ago, Carrara changed the default camera shape to have those two "film reels" on the top of them. I don't really know why they did that but I'm guessing it was because users were having a hard time looking at a camera and determining if it was upside down or not (the original shape of the camera was a simple block and cylinder). Regardless, the "view point" of a Carrara camera is the hotpoint (unless you moved it and if you did, you're going to be messed up).
What we're trying to do here is get the camera to render an image of the sphere facing dead on from a line straight off the center point of the sphere. So, the view point of the camera needs to be at z = 0 and x = 0. The Y value has been determined for a specific reason (we'll get to that).
As you can see, I've got four lights in this scene. They serve specific functions which we will also get too.
5.) Turn of ambient light in the scene settings!