GD Framework Header Styling Issues

Hi, I’ve have almost completed my web page and I’m now having issues with the design of the header. I have done my own picture in photoshop and having the following issues:
1. Unless I add the ‘title and tagline text, or logo’ the picture comes up very small at the top and the title and headline text then disappears when you hover over the website address. If I add the title and tagline text it looks horrible and appears across my picture, the same when I add the logo. I want to remove both logo and title text and just have the picture, but I want the picture be just as big, how do I do this?
2. The picture is cut off on a mobile device, is there anyway around this?