There are two parts to setting up a new page in WordPress: Making the page, and adding it to a menu.
Create the page
- Navigate in the admin bar to “+ New” -> Page.
- Title your page
- Add page content
- Add Excerpt and Featured Image in Page settings
- Assign a parent for the page in Page Attributes
- Publish the page
Adding the page to a menu
- Navigate to Appearance -> Menus
- Select the menu to edit (click Select after choosing the menu)
- Look for your page at the top of the Most Recent tab, or search for it there
- Check the box for the new page, click Add to Menu
- Drag it up to the appropriate position in the menu (right or left changes hierarchy).
- Save the menu.