WordPress has an awesome menu builder built in, allowing you to create awesome menus you can drag and drop to sort, and drag to indent items you wish to turn into a sub-menu.
This article goes over some of the functionality of the menu builder.
Create a new menu
How to add pages to your menu
Creating a drop down menu
Creating a drop down menu with custom links
Do you want your parent page to not link anywhere? Use custom links to achieve this!
Hint: If you don’t want your item to act like a link, remove the # once it’s added to the menu (the # is necessary to add it in the first place).
Setting a theme location
When Secondary Navigation Add-on is activated
When Menu Plus Add-on is activated
Adding Custom Classes
Opening in a New Window/Tab