Drawing a Box

Try it.

%!
%% 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
showpage                % We're done... eject the page