Creating menus is obviously one of the most important part in letting your customers flow through your site. To get to menus, you can go to the customiser and click on menus.
From here you can create an unlimited number of menus, which is an incredible function to have available. These can then be placed in the areas your theme allows you to. These can be in the header, footer and sidebar.
For the most part, you need to get your main menu done first, as discussed in the video.