WordPress’ navigation menus are one of the best features WordPress has to offer. The menu builder allows you to build regular and dropdown menus using a very simple drag and drop interface. You can then insert your menu into your theme without touching any code.
Navigate to Appearance -> Menus to begin. On the left side WordPress will tell you how many locations your theme supports. Most themes have at minimum one menu location, which is above or below the header.
Using the page and category selector on the left side you can easily add any page or category page to your menus, however you are not limited to them. Using the ‘custom links’ section you can add any content on or off you website to your menu, such as a post.