Full-length Header (Navigation Wrapper) wanted for top of Highend "Simple Blog"

I would like to change my navigation wrapper to fit the full length of the blog. Would you be able to help me accomplish this? I did look up the question and found a similar one, where special CSS info was provided to the customer to insert into her general settings. I truly appreciate your help. In addition to this, please also let me know what I will need to adjust the pixel size of my photo to fit the new navigation wrapper settings. Thank you again.