For parametric parts, pads are automatically created. However, once you have fully created a parametric part you can add additional pads.
You can add a pad by clicking a pad in the 
group in the Add menu.
Click 
to toggle between and
TPH Pads
Click 
to add a rectangular TPH pad.
Click 
to add a circular/elliptical TPH pad.
Click 
to add a polygonal/curved TPH Pad.
SMT Pads
Click 
to add a rectangular SMT pad.
Click 
to add a circular/elliptical SMT pad.
Click 
to add a polygonal/curved SMT Pad.
If 
is visible it sets the size of pads added. So when pads are added they have a fixed size. If it is not visible then you define the pad sized by dragging the mouse to define the pad size.
is used for setting pad number.