How on earth do you a draw a 3D shape?

I would get some isometric graph paper and draw using that. In an isometric drawing, each measurement (height, width, length) is drawn using the same distance but based on a 60° grid.

Check the picture below, for examples and the link for more on isometric projection.

You need either 'dotted' or 'graph' paper'. You are trying to put a 3-d object into a 2-d plane. 

Prism

Draw a triangle. Then from two corners/nodes of the tringle draw a pair of parallel line, of the same length at an ngle of say 30 degrees.  Then at the end of the linesdraw a connecting line , parallel with the corresponding side of the tringle. 

Cylinder. 

Draw a circle. Draw a pair of parallel lines of the same length and at the same angle, say 30 degrees. At the end of the parallel lines draw an convex arc corresponding to the convex arc part of the circle. 

Sphere. 

Draw a circle. Then from the top to bottom draw another arc inside the circle. Similarly draw a second arc inside the circle, from left to right of the circle. The two arcs will cross/intersect, but NOT at the centre of the circle.

NB Have a look at diagrams in maths text books. 

NNB Ask an artist to show you how to do it. 

Hope that helps!!!!!