To begin. You will need to log into the Dashboard/Admin Area of WordPress.
If you need to know how to do this – click here.
To add Pages to the main menu:
Click Appearance (Left-hand menu). Then click on Menus.
By default, you will see a list of pages displayed on the left-hand side menu. Select your new/existing page and click Add to Menu.
The page will now appear on the right-hand side within the menu structure.
Drag and drop your new menu item/page to the correct location in the menu structure.
Click Save Menu to complete.