Do you have problems inserting Adsense directly into your Blogger XML code without using the Page Element? For example, if you want to put it below the Post Title but above the post? Read a good instruction on how to do it here. If you want to put the code in the Post Page only but not in the main page, read how to do that here. Example: click on this post Title and see how the ads appear above this post (if you're not in the Post Page yet).
To do either of the above, you have to modify the Adsense code a bit. The modification is called parsing the code. Read more about it here and use this page to automatically parse your code.