I have read about websites finding sponsors. How do you find advertisers?
Essentially, what you are hoping to do is conduct a publishing operation for which you will sell advertising – just like a magazine or newspaper does. If so, you are in luck. Advertisers are flocking back to the web as an advertising vehicle.
However, while the numbers may be up, the nature of online advertising has changed. At one time, sites solicited banner ads. Now online advertising has become much more targeted and measurable. For example, the growth of Google's pay-per-click AdWords system has allowed companies to place ads next to internet searches, and pay only if users click that ad.
Advertisers will no longer put an ad on a site simply because it exists, or because it has traffic. Now the site has to be the hub of a community of like-minded people to whom the advertiser wants to gain access.