The Main menu block is located on the left side of your page in the Sidebar first region. It is a vertical list of links to your pages.
By moving the Main menu block to the Menu bar region it will be located at the top of your page and will display as a horizontal list.
- Click Structure then Blocks on the Admin menu.
- Find the Main menu block in the Sidebar first region. Use the drop down menu to move the block to the Menu bar region.
- Click Save.