Image in header

Sounds reasonable – Can you set up a Child Theme first?
http://codex.ww.wp.xz.cn/Child_Themes

Can you then copy ‘header.php’ from your theme and paste it into your Child Theme directory?

Replace the contents of your ‘header.php’ file of your Child Theme with the contents of this PasteBin’d page http://pastebin.com/Ecn4Yr4h (the code bit)

You need to change line 37 so that it references the image you want.
http://www.w3schools.com/html/html_images.asp