Post Script
Links to tutorials etc.
Simple example of drawing lines and rectangles
%!
%% Draws a one square inch box and inch in from the bottom left
/inch {72 mul} def % Convert inches->points (1/72 inch)
newpath % Start a new path
1 inch 1 inch moveto % an inch in from the lower left
2 inch 1 inch lineto % bottom side
2 inch 2 inch lineto % right side
1 inch 2 inch lineto % top side
closepath % Automatically add left side to close path
stroke % Draw the box on the paper
% 2)
5E-1 setgray % set color for next action(s) (50% gray)
newpath % Start a new path
2 inch 2 inch moveto % 2 inches in from the lower left
1 inch 0 inch rlineto % bottom side relative to starting point
0 inch 1 inch rlineto % right side (relative)
-1 inch 0 inch rlineto % top side (relative)
closepath % Automatically add left side to close path
fill % Fill with set color
% 3)
1 setgray % color: white
newpath %
2 inch 2 inch moveto % back to lower left of square 2
1 inch 1 inch rlineto % diagonal to upper right corner
stroke % draw
0 setgray % color: black
%newpath %
2 inch 3 inch moveto % top-left-corner of gray square
1 inch -1 inch rlineto % diagonal to bottom-right corner
stroke % make it a line
showpage % We're done... eject the page