To add new menu blocks, use the "Add menu block" link on the administer blocks page, admin/structure/block. You will then be able to configure your menu block before adding it.
When adding or configuring a menu block, several configuration options are available:
Basic Options:
Block title For menu trees that start with the 1st level, the default block title will be the menu name. For menu trees that start with the 2nd level or deeper, the default block title will be the title for the parent menu item of the specified level.
For example, if the active menu trail for the Management menu is: Administer > Structure > Menus > Main menu, then a menu block configured to start with the 1st level of the Management menu will display a block title of "Management". And a menu block configured to start with the 3rd level of the Management menu will display a block title of "Structure".
Block title as link For menu trees that start with the 2nd level or deeper, the default block title will be the title for the parent menu item of the specified level. If this option is checked, the block title will be a link to that menu item.
Administrative title To help identify the block on the administer blocks page, you can specify a unique title to be used on that page. If blank, the regular title will be used.
Menu name Select the menu to use for the tree of links.
Starting level Blocks that start with the 1st level will always be visible. Blocks that start with the 2nd level or deeper will only be visible when the trail to the active menu item is in the block's tree.
Maximum depth From the starting level, specify the maximum depth of the tree. Blocks with a maximum depth of 1 will just be a single un-nested list of links with none of those links' children displayed.
Advanced options:
Make the starting level follow the active menu item If the active menu item is deeper than the level specified above, the starting level will follow the active menu item. Otherwise, the starting level of the tree will remain fixed.
Expand All children of this menu will be expanded.
Sort Sort each item in the active trail to the top of its level. When used on a deep or wide menu tree, the active menu item's children will be easier to see when the page is reloaded.
Fixed parent item If you select a specific menu item, you alter the "starting level" and "maximum depth" options to be relative to the fixed parent item. The tree of links will only contain children of the selected parent item.
Classes:
Themers should look at the myriad of classes added to the