If you plan to use Autodesk Revit for MEP fabrication detailing, see the following resources in the Revit Help to learn how to use Revit:
For specific information on how to use MEP Fabrication detailing features in Revit, see the following sections in the Revit Help:
Additionally, this Fundamental Training video provides information on how to convert a Revit design-intent model to a Fabrication CADmep model: