Screen printing is a process that remains somewhat the same no matter what you are printing on. Although your processes do change with different substrates. Mesh can be made of many types of materials. The most common would be polyester and nylon while some use stainless steel. It is next to impossible to find "silk" screen or mesh as the industry has changed the standards due to the fact that silk is to costly. To learn more about mesh try: www.dynamesh.com
There are many ways to make a "screen” you need a frame, mesh, means to stretch or tension the mesh and a means to fasten the mesh to the frame.
For wooden frames you tension the mesh to the desired tension. Then you allow the mesh to sit and then retention until you relieve as much screen stretch as possible then you fasten the mesh to the frame. With wood you use staples. BEFORE stapling you stretch a nylon material made for stapling down one edge of the screen and then staple the mesh to the frame. Staples should be angled and must stay on the stapling material or you will rip the screen.
For roller frames you attach the mesh using plastic strips that slides into a groove on the frame then you use wrenches to tighten per manufacturers instructions then repeat until you obtain the desired tension after removing most of the screen stretch.
Aluminum frames follow the same process as wood only you use a special glue to hold the mesh to the frame instead of staples.
Hope this helps
American Apparel are good tees for screen printing. I have been searching the web for some cool t-shirt design web sites and i have a t-shirt on order from CustomInk.com They are a really cool website and fairly cheap, you can go online and create your own t-shirt design and see what it looks like before you decide to buy. Here's a link if you're interested: