Now you just need to find a spot to hang your poster. Attach 1 pin in a corner of the poster and use it to place the other magnets. My poster aren't...
In the dorms our walls are push-pin friendly. I wanted a way to hang some posters of my drawings but did not want to use push-pins because they create holes. Luckily I love magnets. This solution should allow you to easily take down your poster and post it up some time else without creating and widening holes in your poster.
And just to advertise myself, if you wanted to see the Ringo Starr drawing, here's a link to my drawings on flickr.
Start by gluing one square magnet to a pin. Use this to determine the orientation of all the other magnets. More for entertainment purposes than practicality, I place the magnet I want to start glueing under my desk and check to see if it attracts or repels the glued pin/magnet above. Glue the 2nd pin to the top face of the magnet under the desk. Two pin/magnet pairs should repel when facing opposite directions.
Step 3: Glue Magnet on Poster
Depending on the wight of your poster, use either the larger or smaller magnet squares listed in the Requirements section. My posters were light enough that I used the smaller magnets. I positioned them so that they would be in the inner most quadrant of a larger magnet placed over it in the corner of the poster. This is so the larger pin/magnet could be placed further in and not seen when hung. They should be glued so the pin/magnet made in the previous step will attract with pin facing away form the poster.