You can register a boar/semen through the following path:
Management> Breeding Herd> Data entry> Boars> Purchase > Add
Click on the Add icon 
It will show the "add purchase" screen
Mandatory fields will be shown with *, while the other fields are optional.
After filling all the data, just click on the "save and close (if there is no other entry to add) or save and continue (to add another boar entry).
The birth date must comply with the "rules for male entry" settings.