How can I keep the same header when navigating to different URL? such as;mywebsite.com/homemywebsite.com/aboutusmywebsite.com/findus
You would need to have the same header code in place on each of those pages. Each bit of text after your / is a folder, and in each folder, typically you have a index.html file being served to your website visitors.
There is a method to use a format like this if you are interested:
More information about that technique can be found here: http://forums.tumult.com/t/linking-to-a-specific-scene-from-inside-and-outside-of-a-tumult-hype-document/1103