How to add a second menu

I used the menu option under appearance to add a top navigation level to my site. Now I want to add a footer menu, so I used the menu option under appearance to create a second menu, but I have no idea how to get it onto my site. Do I need to add a special line of code to my footer.php file? I’m new to WordPress so I’m kinda trying to figure this out as I go along. Do I need to use a widget? Any help would be appreciated!