Print out this stencil PDF, cut out the black spaces, and then paint over it on the shirt using the fabric paint. If you're too impatient to work with fabric paint, feel free to print out this design on Iron-On Printer Paper found in many craft stores.
Here's an amazing step-by-step tutorial on How to Make a Stencil on a Shirt. If you'd rather do silkscreening, instead of stencil, go here for a Quick-n-easy tutorial on how to make your own silkscreened shirts!
For more cool stencils, check out Stencil Swap.
Check out these cool finished Star Wars Stenciled Shirts: