To advertise your website or custom app on Facebook, click the create ad button and then select “search by url”. Then you can enter in the url of the website or custom app you would like to advertise.he rest of the ad setup in terms of how to write a good ad, how to target that ad, and how to optimize your ad spend is the same as above. That’s our article for today. If you are ready to start advertising on Facebook go here to learn how to get a free $50 Facebook advertising coupon.