You can link the Pages, Post, Custom Links and Categories to the Main Menu.

To create a Menu Item, navigate to WP Dashboard > Appearance > Menus.

• Select a Primary Menu to which you wish to add the Menu Item
• Choose a Content Type from the left side of the screen. Expand the section and select the Items you want to add to the Menu.
• Click on “Add to Menu” button
• The Menu Item will be added as the last item in the Menu Structure. Re-position it if required, by dragging and dropping it to the target position. You can drag a menu item a little to the right to make it a submenu of the immediate above item.
• Tick the “Primary” checkbox from the “Menu Settings” panel.
• Click on “Save Menu” button