General question on autocad in designing 3D models.

[liftmys10]

I have experience for 9 years working on AutoCAD Civil 3D, but now I want to implement that knowledge in creating models. I would like some general idea on what software people are using when they create a for example CAT D11 on CAD. Once they create that on CAD, how does one start building the pieces? Do you simply send the CAD file to a CNC machine and next thing you know you have that piece made? Any general step by step procedures would be appreciated. Thanks.