First search the : Triggerdata.txt in your war3patch.mpq . Ten , you must find a 'block' of variable type (integer ,real ... ) .There you must add your var type .
After this , go in UI\WorldEditStrings.txt and search again .
Regions that exist on map are like units that already exist on the map. They have strange names. So to be able to get that "name", just create a GUI trigger, refer to the region with an action and then convert to JASS. You should be able to find the region's name converted as well.