Do you have new adsense account from google, and try to add to your joomla websites? You may do these,..
-Find Google adsense module for your joomla.
-Upload your module file to your joomla through your admin panel.
-Set your module, and publish it.
This link where you can find the module and also a guidance how to add your adsense module to your joomla, clearly and easy instructions.
http://www.siteground.com/tutorials/joomla/joomla_adsense.htm
