Well done into taking the plundge. It is not stat hard.

If you want theory go here http://www.geocities.com/spokeanwheel/

A good calc I use is here

http://www.recumbents.com/wisil/spokes!.asp

When it says rim dimiter you need to find out the effective rim dimiter of your rim so google for erd Velocity deep V or efective rim dimimter Velocity deep V