If you want to insert adsense or any other ads above title of the post or below title of the post then open single.php from
Appearance->Editor->Single Post
And now search for the code
<?php the_title(); ?>
This is the code to display title of the post. So if you will put your code just before <?php the_title(); ?> then ad will display above title. If you want to put ad below title then put ad code below <?php the_title(); ?>
Now you must be interested in knowing how to put adsense code below content of post.
Happy Blogging 
About Rahul
I use a Woo Theme and paste the code just above the content, it gets adjusted itself. Like that.
I want to place Infolinks Related Tags below the post title, so I inserted right below the mentioned code, but it is NOT working. Does it work for Infolinks Related Tags?
Any idea how to put 2 units above post beside each other..??