Hi Cheryl-
I tried to take a look at the site you sent over, but for me it just goes to the DreamHost default page. It’s tough to say what might be going on with your image without taking a look at it. Can you double-check the URL for your staging site and reply so we can take a look for you?
When you say “header image,” are you working on your Logo, or the background image, or possibly the image at the top of the homepage?