This must be OBIEE 12 Maps week at Oracle.
First (Feb 26, 2016) Business Analytics - Proactive Support published OBIEE 12c and MapViewer - Common Issues and Troubleshooting Steps that points us to support document Doc ID 2109293.1
Next (Feb 29, 2016) Customer Engineering & Advocacy Lab (CEAL) published OBIEE 12c: Creating a Custom Layer in MapViewer for use with VA that points us to support document Doc ID 2105521.1
Naturally, it might be a good idea to read first the original documentation at chapter 12 of the System Administration Guide.
Update (Mar 28, 2016):
A little later Andrew from http://bisoftdiary.com/ added the post Oracle Map builder simple map.
By the way, usually when you want to work with your specific geographical region, you have to upload the relevant geographical data to the DB and Associate it with the relevant BI content. When your data contains Latitude and Longitude data you can have maps without any such configuration.
For example in this Analysis (Answers) this is a map of battery disposal locations in northern Tel Aviv (there is no Tel Aviv specific information in my spacial database):
To get it, select the Variable Shape type in the Analysis Map component:
Then,Custom Point Layer:
And assign the relevant Lon, Lat columns (or their combination as a single column):
Similar works with VA Project:
Just remember in the object properties (in the Map Tab):
to select Oracle Maps as Background Map instead of the default Thematic Map:
By the way, if you have problems with background of the map, the document "Background image in maps do not display after recent BICS March 2016 Upgrade (Doc ID 2116983.1)" at support site, might be handy.