The use of menus are described here,
The grid shows all menus currently defined for the site. Each record will contain information about the name the menu will have in the site structure tree, the name of the presentation used, and a field stating whether the menu has any menu items defined.
This will start a wizard that is used to update the information about the menu and/or the presentation used by the menu. You can read more about wizards here.
On the first page you can update the basic information about the menu (name and comment).
On the next page you can change the presentation used by the menu. If you just press Next you will keep the currently selected presentation and go to the next page.
In order to change the presentation press the button "Change presentation". You will then be able to search for presentations by entering your search criteria in the "Search for" field and press the "Find" button.
To select a new presentation press the "Select" button for the presentation you want to use for the menu. This will also take you to the next page.
The last page is a confirmation page. Press Finish to apply your changes or Cancel to discard the changes.
You can also press Back to go back and change the selected/entered values.
You are not allowed to delete a menu if it is used in the site structure tree.
On the view page you will be shown information about the menu - and information about the presentation and the content loader used for loading the menu.
The Roles button loads the roles maintenance for the menu site element as a pop up window.
Contains the name of the menu.
The name of the presentation currently used.
Explains if the menu has any menu items defined.