Legend views are common to all flavours of Revit (Revit Architecture, Revit MEP and Revit Structure)- so once you can use it in one flavour, you’ll be conversant with it in the others. So what is a Legend? Simply put, it is a way of displaying a list of various model components and annotations used in a project.
Also included on this page is a tutorial showing you haw to work with CAD files in Revit.