Affiliate networks are starting to get saturated to be quite fair, because of the accessibility that to the industry that HasOffers provides, it seems a new network is popping up every couple of days, a few thinking they can ball around throwing CPM ads all over the place.
As a result, very few offers have their own USP's, and really can't deliver selling points on more than payout times. You have your big players like NeverBlue, Azoogle (Epic Direct), which are directly financed by hundred million dollar parent companies, a couple of other good ones - and then your average network no one has ever heard of, let alone wants to do business with. Only so many can offer "the best payouts in the industry" before it starts to have absolutely no meaning. I'm not saying that it's an impossible industry to enter, but what I am saying is that based on your financing and current knowledge, I definitely wouldn't attempt to set-up an affiliate network, at least not at this stage.
Affiliate networks live of affiliates, which requires traction to get affiliates on board. To get traction now with such a vast of no-name affiliate networks out there, and more coming out everyday, you need a game changer which offers something of mega-value to affiliates which other networks simply don't.
EDIT: As for how they operate, your job is to find advertisers who want to work on a cost per action (CPA) model. You help them find a profitable CPA model for them, charge them on a per action basis (lead/sale/call/click/etc), knock a % off the top, and then pay the rest to the affiliate.