You can restrict the giveaways at two levels: Country and ZIP codes
Country: 'Campaign' --> Click on your campaign text (Shown in blue color) --> '1.Setup'--> 'Restrictions'--> 'Campaign Allowed Countries' - Here enter the countries that can view and participate in your campaign
ZIP code: 'Campaign' --> Click on your campaign text (Shown in blue color) --> '1.Setup'--> 'Restrictions'--> 'Campaign| Visible only to the entered ZIP/Postal code' - Here enter the ZIP /Postal codes. So the way this works is that a restriction pop up will appear that entrants will need to enter their ZIP codes. People are only allowed/shown the campaign if and only if the entered code matches with the codes you had entered, the campaign
