The main advantage of this Adsense ad placement is that it has the highest CTR on most of the blogs. Adding this ad unit is very simple and requires a code snippet before and after your regular Adsense ad script.
If you want to add a ad unit in top right corner of your post, then include the red lines below in your ad code:
<div style="float:right;">Your Adsense ad script</div>
If you want to place ad unit at left corner, change the float tag to "left":
<div style="float:left;">
Your Adsense ad script
</div>
The most appropriate for this ad placement is 250×250 square ad unit. Placing AdSense unit in the middle of the post, may disturb the reading flow, so I'd recommend to have ad units at the beginning of the post.
If you have any query adding this ad unit in your blog post, just leave a comment below.