You can register a sow/gilt through the following path: 


Management> Breeding Herd> Data entry>  Females> Purchase  > Add





Click on the "Add Gilt Purchase" icon And the following screen will open



Click on this icon for an open sow, and this icon  for a pregnant sow purchase.


After filling all data, just click on "save and close (if there is no other entry to add) or save and continue (to add another entry).