Those who have monetized their blogs with adsense or any other advertising network may find it difficult to add ad codes inside the template in areas like below the post and below post title. Here is a very brief tutorial on how to add adsense code or any other banner code below the post.
==> Go to Blogger dashboard > Theme > Edit HTML
==> Search for <data:post.body/>. There is one of such code in 3 of the themes. Place the ad code below it and save theme. If you find more than one <data:post.body/> place the ad code below the second one and save theme.
==> Go to your blog post to view. The ad will be displayed below the post on both web and mobile.
If you follow the above steps closely, you should be able to add ads below your blog post on blogger new themes.
For the old themes search for <div class=’post-footer-line post-footer-line-1′> and place the ad code below it. Two of such codes exist. The first is usually for mobile and the last is for web.