Custom graphic page headers

Greetings, I am working on a website at https://jdc.media/aada/ and on the page https://jdc.media/aada/get-help/ I want to change the page header to a different image then what is currently shown. I believe this is done in the Elements section where you can make a unique header and set include and exclude rules correct? Is there a article on how this works?

Kind Regards

Chris