yes that's right use an adsense plug-in or if you want just simply edit your current template. In Wordpress, edit single.php. If you're using Blogger blog then, much easier just edit the Post area on the template and there's an option that activates the adsense for each post. By the way what's your blog engine/software used?
Hey!! you cannot place adds on each post... There is a limit for the no. of adds that you can have ..In adsense... three per blog..
Go to Wordpress directory on your computer or into your dashboard and enter the Wordpress Plugin Directory, then upload AdSense Manager plugin. After that, you need to activate this plugin in the Plugin Management onto your dashboard. Now you can add ads but be careful...not too many of them.
What's happening if my blog has only one page and the posts follow one after another? How many ads are permitted?