I want my ads to show in all of a certain area, not just in a sub-region. Do I have to select a sub-region?
You do not need to choose a sub-region, but it's in your best interest. Ads posted in a sub-region will appear when a user drills down to that level, and all ads will be always be shown in the main higher level region. If you don't select a sub-region, ads will only appear in the main region. When a user goes down to the sub-region level, your ads will not appear if no sub-region was chosen. Not all regions have sub-regions.