Creativix Header Will Not Work??

I am working on a new site and this is my first exposure to CSS. I am using the creativix theme and the header will not show up, even when I upload an image. My site is blogsussex.com and this is the header image – https://blogsussex.com/wp-content/uploads/2012/06/headersmall.jpg

I appreciate any advice/help, because I really do not know what I’m doing as far as editing the codes for my page. Thank you!