Headers on Individual Pages

Hi I am having trouble getting headers on each individual menu page. One page is perfect with a full header across the top. Another page has no header. Another has the full header as I would like it, but is repeating the same image below it at a smaller size. I thought it had something to do with the featured images, but I am now just so confused I am hoping someone can help. When I was having difficulty I set up the slider on the front page which appears to be working well now, but inconsistencies on each page are occurring and I just don't know where to start. I would be really grateful for some clear instructions as to how to fix a different photo, of my choosing (not randomized) to the top of each photo. Thanks in anticipation Sharon