How to replace header with custom header image

I recently had to recreate my blog and lost the previous header image which hadn’t been updated since previous version of Kubrick (which offered a custom header option in “Appearance” menu). New Kubrick 2014 has some instructions in the Editor coding selections but impenetrable for someone who knows only basic html. Can you advise me what SPECIFIC code to add to which SPECIFIC template (under Appearance >Editor > Templates) and WHERE in that template to place the added code, and WHAT code, if any, needs to be removed from the original template. Also, in WHICH FOLDER do I place the image in order for the blog to access it? Thank you if you can help!