Step 2) Get your ad code from Adsense website, it should be place within tags as shown below -
<div align='center'>
</div>
<script type="text/javascript"><!--
google_ad_client = "ca-pub-xxxxxxxxxxxx";
/* Large Rectangle */
google_ad_slot = "xxxxxxxxx";
google_ad_width = 336;
google_ad_height = 280;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
Step 3)Go To "HTML" of the blogger post and place the adsense code obtained in step 2 anywhere you like.You are done.
Now you can see the adsense ads appearing wherever you have placed the code in the blog post.The important thing to remember here is that you should not parse your adsense code while trying to place in anywhere in blog posts.