How to Add Adsense Ads below post title onblogger:

First check expand widgets template , The search for <div class='post-header-line-1'/> then add google adsense ad code immediately below that line.

How to show Google Adsense Ads only in post pages:

it's very simple , just add this code

<b:if cond='data:blog.pageType == "item"'>
put adsense ad code here
</b:if>