Change the page header

[junius83]

Hey. At the beginning I'm sorry because I do not know English well, but I did not get help in my forum. I am not sure if I am writing in the appropriate section. I am asking for advice. I changed the background on the page, but I have a very asymmetrical header. Can I give me tips on how to take a photo from the header by a photo, but there was a solid color there. In the image collection the picture looks like. Thank you in advance for all the tips.