If your website header is not visible after installing Hello Bar, the fix could be as simple as choosing the "Pushes page down" option in the Style section. Try this first, save changes, and refresh your website. You should be able to see your header. If after choosing this option, your header is still covered, this is due to your website's theme code allowing for a fixed CSS position for the navigation menu. This is the same code that Hello Bar uses and will conflict with your website's header. You can modify your website's code so that the top navigation bar is not set to fix or absolute. If you would rather not modify your website's code, you can set the Hello Bar to appear at the bottom of your website, or choose a slider, modal, or takeover instead of the bar design.