To add menus in Wordpress please follow the below step:
Step 1 – Select Appearance → Menus from the dashboard.
Then you find a page like the below screenshot.
Step 2 - Select Create a new menu at the top of the page. Enter a name for your new menu in the Menu Name box and select a display location where you want show your menu.Then Click the Create Menu button.
Now your new custom menu has been defined.Step 3 –In this step we add item in our custom menu.
Then you find a page like this.