Don’t worry about design yet. You will design in your theme framework.
Your permalink is created as directed by your option in Settings/Permalinks.
Set order number at 0. Future page order numbers will be marked in intervals of 10 to allow for sub-page orders in between. This determines the order of your sub-pages listed in menus.
If you already know what title names you want to show in your main menu, create pages with those title names. Creating pages will make it easier to show you how to create menus described later.
Click ‘Update’ to save changes, or save as a draft.