[RTTY] Dumb question about pileups

[David VE3VID]

I've got a dumb question about RTTY pileups. The other day I was combing around 30m because the spotting network told me Sudan was calling. When I got there, there were lots of stations spread out around the spotted freq all calling, but I had no idea where the DX station was, or who they were working. It seemed a little random. I must be missing something. Do they work split? I never found the Sudan station signal.
How are RTTY DX pileups organized?  Do I just find an open spot and start sending my call sign. Seems that's what everyone was doing, but I'd never know if the DX station went QRT. Sorry if this sounds too basic, I'm pretty new to RTTY, and never tried a pileup.

Thanks for any helpDavid
http://www.ve3vid.webs.com/