Jetskiron, you're working with something completely different from html. You don't get a file when you make a page or a post, this information is put in the database and retrieved by PHP files. The file you want to edit is in wp-content/themes/yourtheme (look for the header.php), but this goes for all posts and pages. You can make different looks on different pages, but that's a whole lot of coding. The appearance of the page is made with CSS (style.css) and again, the stylesheet is for the whole WP site, or heavy coding.