Info
The first, you need read about menu here: Menus and Links
Create Menu
1. Go to Navigation to create a menu.
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2. Click Add menu to add new or choose any items below the menu to edit.
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3. Write the menu’s name, then choose Add menu item.
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4. Write the menu item’s name and choose the item in dropdown box > click Add.
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5. To make an item to a child menu, drag it under the main item.
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Menu items can also be added to create the same level of a child menu.
Add mega menu to the homepage
Go to Themes > Customize.
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Check Header section > Menu, then edit menu and use the created menu.
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Mega Menu
In the Header section > Add Mega menu
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Sidebar menu
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Only available in header layout 1, 3 and layout 4
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Custom menu
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Only available in header layout 3