Are you signed up for any of the various affiliate advertising programs (Google AdSense, HubPage Ads Program, Amazon Associates, eBay Associates)? You need to get hooked up to at least one of those first before you can earn anything.
From then on it's up to the Internet Gods because your earnings are based on how many page views/clicks your ads get. If you get decent traffic, you'll earn some beer money now and again. If not, you'll be waiting a long time for a payout.