Microsoft doesn't really support a direct mechanism of backup & restore through Azure. You can do an export/import through the Azure storage. I have a blog post about it here. It's not the same thing as a backup.
You could look at Red Gate's Cloud Services utility. It does a lot of what you'd want in a real backup process plus more.
Disclaimer, I work for Red Gate.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood" - Theodore Roosevelt