The pdf in this folder is brief. All the information you need is in
Chapter 4 of the text. 

Remember that in a Graphwin (window), (0,0) is at the top left. When you
move in the x direction it is to the right. When you move in the y direction
you move downwards.

If you want to change this behavior to make movement function just like in
the first quadrant of the (x,y) plane [what we are used to in drawing graphs]
you have to use the setcoords() function.