This theme has one menu, this is the long menu across the top of the page.
Navigate to Appearance > Menus, and follow the on-screen instructions.
Login > Settings > Reading > Your homepage displays… select the home page you have created and not the “latest posts”.
To re-order the menu, you have to add a menu as above guidance.
If you do not add a menu as per above guidance, then the pages/posts you create will show in the menu bar but not necessarily in the order you want them to be in.
If you menu doesn’t show, you need to assign the location. For this theme, it is “Top”. Screenshot below.