Step 1. Open single.php file and in just before </head> tag paste:
<script async custom-element="amp-ad" src="https://cdn.ampproject.org/v0/amp-ad-0.1.js"></script>
Note that amp-ad may still work without this script, but AMP PROJECT highly recommend it for future compatibility
https://www.ampproject.org/docs/reference/components/amp-ad
Step 2: Find <div class=”amp-wp-content”> line. And below the line paste the the code below
<amp-ad width=350 height=100
type=”adsense”
data-ad-client=”ca-pub-95675557XXXXXXXX”
data-ad-slot=”170XXXXXXX”>
</amp-ad>
Step 3: For ad to be displayed below the post search for do_action( ‘amp_post_template_footer’, $this ); and paste the adsense code before the php starting tag which we used in the previous step.
