A Heads Up: I installed MarketPress and as promised "MarketPress will automatically create your Store pages when you click Save changes on the Presentation settings tab." However, for reasons unimportant, I "trashed" the pages created. I then went back into MarketPress settings and changed some settings in the Presentation tab. I saved my changes and no pages were created.
MY SOLUTION: Permanently deleted pages I trashed in "Trash", deactivated/reactivated MarketPress, then returned to "Presentation" tab and saved. The pages were created!