SPDIF output - how to use?

[gloval]

I have this http://us.shuttle.com/specs.asp?pro_id=280 motherboard; a shuttle AN35N Ultra - i just picked up the spdif card for it, plugged it into the header, and i can't figure out how to get it to output a signal to my 5.1 receiver. i'm sure it's something easy, but i'm stumped at this point.