If you don't know what you need then you REALLY don't want to start a network.
I have worked with top companies in the industry that tried to launch their own network with lots of tech savvy and lots of $$ and could not pull it off.
Aside from all the tech and marketing and support aspects there is one fundamental problem you will have.
You can't get enough affiliates until you get enough merchants and the merchants won't join your network unless you have lots of affiliates.
It's a HUGE catch 22!
BELIEVE ME it's TOUGH and there are already too many networks out there.
If you really want to try
www.directtrack.com is the software most of the smaller new networks use.