Reading about these concepts is not enough. You must teach your hand what your mind knows.
Draw the silhouettes of the basic forms from many different angles. I recommend drawing them on gray construction paper. Cut out the silhouettes, turn them over so you don't see your drawing lines, and determine which of the views you prefer and which best describe the forms.
As a further exercise, find several objects that are combinations of the basic forms, such as an ice cream cone, which is made of a half-sphere and a cone, or a Band-Aid box, which is a cube with cylindrical corners. Draw many views of these combined forms on the gray construction paper, cut them out.Turn them over, and determine which you prefer and which give the most information.
These are the silhouettes of the five basic forms.