There's currently no GUI available to manage Countries. The ]po[ country table will maintained by the ]po[ core team. Frequent updates are available from our code repository, so please make sure you are running the most recent version of ]po[. To notify us about missing countries, please use our contact form. You can add countries yourself at any time using PL/pgSQL. Example:
insert into country_codes (iso, country_name) values ('ng','Nigeria');'"
SysAdmins can use the ]po[ shell (http://[YOUR_SERVER]/ds/shell) to perform a DB operation.
db_dml foo "insert into country_codes (iso, country_name) values ('ng','Nigeria')"
Verify country codes with http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 to avoid conflicts with future updates.