Without 3d - there is nothing to make a section of...
In autocad you are typically drawing with lines that may not have a z axis so everything is flat - you cannot really make a section of that other then drawing it.
In revit the components you put in your model are 3d - so you can cut a section and have the elevation already done - you may need to embellish it a bit but for the most part it is done.
To do a section in revit - go to the View tab> Create panel> Section tool. In the properties dialog box you can use the type selector to create a building section or wall section.
You then pick a point on your view and then a second point - this will place the section line and create the section.
You should see it in your project browser or you can double click on the blue section tag and it is a hyperlink to the view.
Is this what you are looking for or is it something else?
LD