This is a very easy thing to do with Blogger. Adding Adsense above the title of each post is known to get you more clicks and make you more money. This is because the Adsense is in prime position, right in the face of the visitor. Adding Adsense to this position in blogger will make it visible above every post you make, and it only needs to be added once.
In the image above you will see two numbers, 1 and 2. Im presuming you are already a member of Google Adsense and know how to generate an Adsense code to paste into blogger, never use the "Add Adsense" tab supplied by Blogger, always go into your Adsense account and make your Adsense code manually, this way you can add a channel so you can track the performance of your Adsense Ad on your site or blog.
An example is this blog http://cashsearcher.blogspot.com/, for my channel name i have chosen "make money blog", this way i can keep an eye on my statistics, from page impressions, to which Adsense Ads are perfoming best on my blog.
So then, make your desired Adsense Ad in terms of size, colour etc. I have chosen a thin link line above my posts, you can choose whatever you think looks best for your site. When you have made your Adsense Ad and have copied the Adsense code, go to your Layout, Page Elements, go to number "1" in the image above and make a new "Add HTML or Java Script" widget. Paste your Adsense code into this new widget and press save. Once you have pressed save, press and hold your mouse's left click button and drag the widget to the desired location, in this case it's above the "blog Posts" box, you will see that Blogger will automatically make a place for your new widget. Press save, then view your blog and that should be it.
Give your new Adsense Ad a few minutes to show up, don't panic if you view your blog and nothing is there, this is normal, it can take quite a few minutes to show up, if you have followed the steps correctly it will show up.
1. Go to your Adsense account, make your new code.
3. Paste the Adsense Code into your new widget > Click save.
3. Click and drag the new Adsense widget to the top of "Blog Posts" Number "2" See Pic > Press Save.
4. Give it some time to show up.
5. Admire your new Adsense and wait for clicks!