HOW TO START AN AD NETWORK?

[double c empire]

Please, give me specific steps. Where should I go first. I have a sense of what it does but I have absolutely no clue on how to start one... i'm clueless!

[Jake]

You could find an ad network site clone script, that would at least save a web developer a lot of coding time.
http://www.kaonsoftwares.com/ad-network-script.html

That certainly sounds like something only someone with experience and a reputation in the industry would tackle, trust is one necessary attribute that can take time to earn. Aside from a lot of paid advertising promotion, having mature accounts on the various webmaster, marketing forums would help one reach prospects.
Some ad networks use quite sophisticated ad server software that requires an expensive fast dedicated server.

[Daniel M]

You could always try the Adquick clone script
http://www.phplemon.com/adquick-2-5-changelog.php

Its got plently of features and if you need anything specific you could get in touch with the script owners.

Building an ad network takes time. You will need to entice webmasters to register on your site.
I think it would be wise to start getting advertisers first before finding publishers.
Once you get advertisers, publishers will just register on your site.