First of all you need to create Google AdSense Code for your blogger follow below steps:

First login Google AdSense account.
Create ad unit any size but I recommend you create 300*250 and save it
Kindly generate ads tag and choose Synchronous ads Type and copy ad code.
Now you need to parse your AdSense code from below tool just paste your AdSense code below tool.
Now you have AdSense Parsed code & now add to blogger from below steps.
Add (Insert) Google AdSense Code on Blogger:

First Login your Blogger account.
Go to Blogger Template
Take a Backup for the safety as a said before.
Click on Edit HTML
Press CTRL + F and find this code : <data:post.body/>
There may be more 1 code like above code but you have to try with all codes.
Now you have to add below code above this <data:post.body/>

<b:if cond=”data:blog.pageType == &quot;item&quot;”>
INSERT YOUR ADSENSE CODE FOR BELOW OF POST
</b:if>

SECOND: Add Google AdSense Ads After Post in Blogger:
in order to insert Google AdSense below post. follow this steps
Create Google Ads like above and Parse it.

Find this code <data:post.body/> like above but here you need to add below code after this code <data:post.body/>
You need to add Google AdSense Code below this code <data:post.body/>

All Done.

<b:if cond=’data:blog.pageType == &quot;item&quot;’>
INSERT YOUR PARSED GOOGLE ADSENSE CODE HERE
</b:if>

Follow all the above steps and insert your Google AdSense ads below your post title and after post easily. Parse your AdSense code from below tool.

http://www.jaysciencetech.com/2016/06/how-to-add-adsense-ads-below-post-title.html

Ok!

ok

cool, thank you