Seriously easy - and cheating slightly
Bokeh means blur, essentially you make the cut out shape the apperture, and make any light source that shape. Its very, very cool.
Cut out a shape into the black paper as small as you can, without being too difficult, and depending on the lens size on the camera you'll need different sizes anyway, so you'll need to experiment a little.
This is a little cheat - literally hold the peice of paper over the camera lens and take the picture (you'll need to do it on manual focus)because it has to be completely out of focus to work. You'll see it work through the eye peice.
Also make the iso as high as possible (definately over 800) and make the lens aperture as small as possible most dslr's only go as small as 5.6
but you can also use a manual camera -they go alot smaller, more like 1.4