Separating header image from site…creating space between site and header

Hi…

Have imported a blog developed using Godaddy Quickblogcast, Godaddy template/colors into Twentytwelve theme. Very much want to customize twentytwelve to look and behave like Godaddy Quickblogcast installation and therefore want to position the header image above the .site/.site-content objects…creating space separator…

twentytwelve site and Quickblocast blog header/image links:
twentytwelve installation
Quickblogcast static page

Have tried margins, padding, pixel coordinates..latter I don’t like given twentytwelve is developed with percentages etc. for different devices..

Any ideas are very much appreciated…

Thanks much..
Denise.