The account screen contains a section that lists all the maps that belong to your account. Most customers operate just fine with a single map to manage all their layers but there are reasons why you might want to have additional maps. See Multiple Maps and Shared Layers.
How to create a new map
You must be the account manager to create a new map. You create a map by clicking the "Add New Map" button on the map section of the account screen. By default a blank map is created with no layers. If you want to create a new map with a set of prebuilt layers then click the "use map template" link. This will prompt you to select one of your existing maps to use as a template for this new map. When you create a new map from a template, the new map's layers will be formatted like those of the template but each layer will be blank. The contents of the template layers (ie. "Features") are not copied over. Once the map is created you grant other users permission to add layers to the map by opening the map and selecting User Permissions. Then give those users the "Map Manager" permission.
How to change the name of a map
Open the map and select Map Properties from the map's menu.
How to set the initial viewing area of a map
Open the map and then zoom to the desired viewing area. Then select Map Properties from the map's menu and click "Use Current View".