Draw out and separate your design into each of the colors it will use. Take into account not just each color but where each color is located and which colors will overlap others.
Create one individual stencil sheet for each shape in the design of the same color. There are multiple ways to do this: Draw and cut them out of paper, or create them on a computer and print them out on transparency sheets.
Coat each printing screen with emulsion ink, so the ink covers all of each mesh screen. You need one screen for every stencil sheet; lay the screens with their wood frames pointing up as you apply the emulsion.
Place each stencil sheet onto its own individual printing screen over the emulsion. The opaque part of the sheet should be the shape that will be colored with ink and it should face forward.
Leave the screens and the emulsion exposed to light so the ink will harden. The exact amount of time can vary, but exposing the emulsion directly to ultraviolet light will be the fastest.
Remove the sheets from the screens after the emulsion hardens and run water through the screen. The emulsion that was beneath the stencil should still be soft and run out of the screen creating your screen printing stencil.
Place the first stencil onto the shirt or other object that you are printing the image on. This is the color that is beneath all the other colors on your potential image and won't overlap any others.
Apply the correct color of printing ink to the screen and sweep it over the entire screen with a printing block -- a square or rectangular rubber block that is flexible. Make sure you press the ink over every part of the stencil.
Remove the screen to reveal the colored shapes printed onto the surface. Wait for this ink to completely dry and wash all ink off the block if you are going to use it for the next color.
Repeat these steps for each of the colors, making sure you go in the correct order for your design. The color that overlaps all others must go last.