2010 weaver. Ok. I found the functions.php file. Now what?
Ok. It gives me the option to crop so something bigger should work.
My image is 160×48.
The website says: You can upload a custom header image to be shown at the top of your site instead of the default one. On the next screen you will be able to crop the image.
Images of exactly 940 × 113 pixels will be used as-is.
