First you want to draw or print your design so that you can trace it onto the screen later. Here is the Saco logo that I designed. (croakies and oars have proved to be vital when navigating the mighty Saco)
Next stretch the screen material within the hoop and tighten it as much as possible. Then glue around the edges with the mod podge to keep it in place. After that dries trace your design onto the screen. Fill in the entire negative space with mod podge and let it dry. IMPORTANT: whatever is covered with the glue will NOT print. Where there is NO GLUE the ink will pass through the screen and onto your shirt.
From there you just place your screen on whatever you're going to print on and make sure to weigh it down so that nothing shifts. Using screen printing ink, paint over your screen using a foam brush. This process took quite a while with the pinnies because each screen had multiple names on it so I had to make sure that no ink spread beyond the one name that I was printing, and then the screens had to be washed and dried in between each print. Also each pinnie had a print on the front and two on the back (names and numbers) and the shirts had to dry overnight between each print!
Here are some pictures of the end result...