Menus are used to provide a way for end users to navigate through your website.
You could require users to use the search widget, however, that would not be the easiest way to use your website, in most cases.
To access your menus, go to Appearance > Menus.
You theme will have one or more menu placeholders. You will need to create a menu that can be placed inside the placeholder.
Clicking on the “create a new menu” button at the top of the page will create a new menu, otherwise, you will want to select a menu from the drop down list, and click on the select button.
This will select/create a menu for you to work with.
The menu page is broken into 2 sections. On the left is a list of possible items you can add to your menu. By default, these include pages, links, and categories. Additional menu items may be found based upon custom post types that have been added by plugins or other methods.
Adding Internal Links
To add a category, or page, you will see a list of check boxes. Check the boxes that correspond to the elements you would like to add to the menu. Then click on the Add to Menu button.
This will add them to the top level of your menu. You can then rearrange the order of the menu items after they are added to your menu.
Adding External Links 
Want to add a link to an external website? Then you will need to click on the links section on the left hand side of your screen.
Here you will have a simple form to enter in the link to the external website and the link text.
This can also be used to create a link to your homepage. Just put “/” (without the quotes) in the URL field to send it to the home page.
Creating and Editing WordPress Menus was originally found on Access 2 Learn
