Google adsense is your best friend. You can find some very helful information on how to accomplish this by James at:
http://www.jamestadeo.com/dolphin/boonex-dolphin-tutorial-how-put-adsense-in-profiles.php
and:
http://www.jamestadeo.com/dolphin/boonex-dolphin-tutorial-how-to-add-google-adsense-to-dolphin-blog.php

Based on the prvious version of dolphin, but you should get the idea. Either similar or the same process.

Google adsense ads can be placed almost anywhere on your dolphin site. see more In blocks on specific pages. Or even in the header/footer areas of your site. You are only limited by your imagination.

Get an account from google at:
http://www.google.com/adsense for starters. Ads can be customized within your google account for size and colors to match your site to name a few.

Google pays per click x-amount which varies depending on the ad.

There are others out there, but adsense seems to be the more popular, and one of the better paying.

If you have some other ads you want to go with, they can be inserted into your pages the same way.

good luck.
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