On the scenario for Genghis Khan when I open up the notepad for the worldbuilder save and I want to extend the map eastwards and southwards, How do I do that?

Could I go to the map section and where it asks for the width ans the height can I change the numbers of tiles and that would just make the map longer and wider in the east and the south?(I hope people understand what I am talking about:blush: )
Thanks for any help.:)