A menu template is the easy way to display your WordPress menu anywhere on your website.
First of all you need to create your own menu using WordPress. This is very easy to do, since WordPress offers a very user friend user interface. To do this go to Appearance -> Menus and create your new menu. If you need a guide on how to check out the existing WordPress Menu Guide here
When you have a WordPress Menu created you can start creating your own template for it. Go to Custom Menus -> Templates and start creating your template.
You have full control over your menu display if you wish to use Advanced Custom Nav Menus Templates. You can configure your menu display using default WordPress Menu Options or if you are a developer or if you need more complex control over the display you can configure every aspect of your menu display from the Advanced Options section.