Your best bet is to check out johnbridge.com
Start with the "Liberry" (couple good threads about deck mud and building showers): http://www.johnbridge.com/vbulletin/...isplay.php?f=8
They are also very helpful over there, so if you have additional questions, just post them up and I'm sure you'll get some excellent help.
Before you build the shower, you may want to look into Kerdi or other surface applied membranes. They have several advantages over a traditional shower. If you do build a traditional shower, do lots of reading and take your time. A traditional shower can work great if it is done correctly, but there are several spots where people typically make mistakes when constructing a traditional shower pan.