godaddy – How do I redirect example.com to http://example.com?

I have a blog on blogger.com for which I have got a domain name from godaddy.com. Recently, I decided to put some Google AdSense ads on it to see how it works.

The problem I've encountered is that AdSense does not accept the URL
http://www.example.com, apparently it has to be http://example.com
My blog is available at example.com and www.example.com
but not on http://example.com, as Adsense requires.

I've been looking for an answer for a few hours now, but all I could think of was redirecting to the naked domain (which I already did) and editing the robots.txt file (which I have no idea ).

Every advice is greatly appreciated.