To display ads on your website or blog you need to register with a company that provides ads which can be placed on your site or blog. Google AdSense and Bidvertiser Publisher's section both provide such ads. Its worth noting that these companies are both well established and have good reputations so they wont approve your site to display ads if it contains any hate speach or the like or any adult only content either, there are other exceptions but those are the main two, basically family friendly sites work best anyway, so no loss.

When you register either Google or bidvertiser will ask a few questions relating specifically to your site and its contents and purpose in order to supply ads to your site that will match your content as closely as possible. For every time that someone clicks on one of those related ads that you display, you will earn a percentage of the highest bid paid for that ad. This is generally fairly low amounts per click, anywhere from $0.04 to $0.28 but i had a click recently that earned me $0.90! Although thats nothing special i wasnt even near my laptop at the time and because I'm from South Africa that translated into R9.00 for a single click! Since setting up the site i haven't touched it and its earned me a few handy Rands so far with very little actual effective marketing done to date!

It is genuinely my view that every site online should have ads displayed on it. Its good for the owners of the sites, as they earn from clicks, and its good for users of the sites, as they can browse other similar options easily.

For more info on displaying ads on your site or blog check out the full section here, Advertise on your site/blog