I’ve never really messed with photo emulsion. I like the look of hand cut stencils too much to mess with all those chemicals. Here are some links to get you started if this is how you choose to roll.
Screen Printing: Cheap, Dirty, and At Home
THIS awesome guide even suggests that you reuse old picture frames for your screens. You can’t beat THAT! Perhaps a bit weak on the specifics of leaving the photo-emulsified screen out in the sun..
Learn how to screenprint your own t-shirts from Make:
This vid gets a little silly when they add blinking LED eyes to the wolf, but it’s a solid introduction to what is for me the mysterious part of emulsion screen printing… exposure.
How to Silk Screen
A decent portrayal of the emulsion screen printing process. It’s not going to blow your mind but it will help teach or reinforce the basics of the process. Also they use exposure machines.
How to Silkscreen Posters and Shirts
A solid photo emulsion screen printing tutorial that offers insight into a two-color print.
A DIY Guide to Screen Printing T-shirts for Cheap
An all-text guide. It might make a good supplement to your overall graspage of the concept.