It depends on the type of downloadable content you are offering. For example, if you are offering digital downloads, such as audio or video files, then you may want to consider using an ad service like Google AdSense, which can be used to monetize the content by displaying ads on your site. Other options include affiliate programs, such as Amazon Associates, which allow you to earn commission on products purchased through your site, or pay-per-click (PPC) services, such as AdWords that allow you to advertise specific products or services on your site. The exact steps to monetize your downloadable content will depend on which ad service you choose, but generally you will need to sign up for the service, create ads, and place them on your site in order to start earning revenue.