Select the location for your menu either Primary or Secondary (If you select a primary location then the menu will appear below logo.And if you select a Secondary location, then the menu will appear above logo )
Click on Next
Click on Add Items to add items such as pages, posts, categories, custom and so on to the Menu
To add item on the list click on plus(+)icon
Click on Reorder button to rearrange the items list
Click on Add button to add other items in list
Click Publish
Create Menu from Dashboard:
Login to your dashboard Admin
Go to Appearance > Menus
Click on create a new menu button
Give a name to your menu in Menu Name and click the Create Menu button.
Select the desired items from Pages, Posts, Custom link and Categories
Click on Add to Menu
Drag and drop on items to rearrange the items in list
Check box with blue tick on desired location in Display location of Menu Settings