Check-out the Cascading Lookup Field
Simply click 'Add new item' below the Orders list (you need 1st to sign-in using the details above) and fill out your Region->Country-> City cascading drop-downs.
The Cascading Lookup field allows you also to add your country or city without leaving your New/Edit forrm.
You can use this powerful field type in any SharePoint list or library, and the best news is that it's so easy to use and configure!
For more details visit the Cascading Lookup Plus field product page.
Got any questions?
Contact us at firstname.lastname@example.org