To create a new menu go to:
and click on the "New" icon in the top right.
The "Title" is the title that Joomla will use when it displays your menu.
The "Menu Type" must be a single-word unique name of your chosing that identifies the menu.
The "Description" is a brief phrase that will appear in the back-end menu manager.
Once you have created and saved the new menu, you must add a module to handle the menu. You do this on the Joomla->Menu Manager page. There, you will see your new menu and you need to click on the "Add a module for this menu" link. This brings up the Module Manager:Module Menu definition page.
In the Module Menu definition, enter a title; select the position as 'left'; set access to Public or Registered depending on who you want to be able to see the menu; you should also expand the "Advanced Options" on the right of the page and enter "_menu" in the Module Class Suffix - no quotes. This controls the formatting of the menu items. Finally click the "Save & Close" icon.
At this point your new menu exists but it will not be displayed until you add a menu item to it.
You will probably want to change the ordering of the menus. You can do so from Joomla->Extensions->Module Manager by clicking on your module and changing the "Ordering" field.