First you need Hits, that is visitors.

If you have visitors, you need to find sitable ads for your web site. It depends on what type of visitors you have. Some programs you can try is

www.google.com
www.adhearus.com
www.cj.com
www.shareasale.com

Also try selling ads to local market. If you have site related to eduction, contact local educational institutes. If your site is related to gaming, try affliate programs of some games.