Menus in WordPress help you navigate your site. They normally appear horizontally at the top of the page (For desktops view) or vertically (For mobile view) but can also be placed anywhere on the site.
Step  − Click on Appearance → Menus as shown in the following screenshot.
Step  − Under Menu Structure give your new menu a name. In the picture below, I chose to name it Top Menu. Choose the location of your menu. In this case, I chose Desktop Horizontal Menu. Finally click Create Menu.
Step  − Choose the pages (Or categories) you want to appear on the menu by clicking in the selection boxes. Click Add to Menu.
Step  − Drag to re-arrange the pages in the order you desire. Click Save Menu.