Help With Domain Access and Nodestream

I pray this the right forum to post this inquiry...Hello, I am using Nodestream and domain access module. I have already created the sub-domains I needed. Now my question is how to 'push' (for lack of a better word) content to a particular sub-domain so it's (the article or advert is not visible to the other sub domains.)
The Domains created are as follows Nairobi, Nakuru and Test. Basically I want the articles meant for Nakuru to be either automatically routed using Taxonomy or manually using a sub-domain list/drop down.Need I say am a novice at this. Thank you