It's easy to change Surname and firstname.
Using the context menu:
Set to Root - set person as root (main) person. Marriges are visibles only to root person.
Add a Son - add new person as Son.
Add a Dauhter - add new person as Daughter
Delete a Person - permanently delete of person. Avaible not ever.
Properties - open additional properties
Set a portrait - add a foto of person.
Parents - settings of parents
Add a Marriage - add new person as Wife (Husband)