Hello,
To import cities, first you need to purchase geolocation from here:
https://www.sellacious.com/apps-and-integrations/geolocations
After purchase, you can upload csv file.
Also, If you don't want to buy you have to add geolocations manually one by one. For more help, you can go through the below link:
https://www.sellacious.com/documentation-v2#/learn/geolocation
Hope this helps,
Thank You