There are several ways to create a new map:
Select New Map from the File menu or click the New icon
on the Tool bar. The New Map dialog appears:

Fill in the dialog, specifying the database, mapset,language and new number for the map, then click OK. A Map Editing window displaying the map appears. You set some of the initial properties for new maps in the customisation section of the MAPEDIT.INI file. See Configuration for more details. You can use the map number comobo box to see what map numbers have already been used. You need to select a different map number from any of these.
Alternatively open the mapset and edit the new map (in angle brackets)