Hi Daniela,
You can add biographical or administrative history information directly to the authority record, and then link it to an archival description as either a creator, a name access point, or (depending on the standards template you are using) some other kind of relation such as contributor, collector, broadcaster, etc.
When you add a creator name or a name access point to an archival description, AtoM will automatically create a new stub authority record if you are not linking to an existing one. Once your description is saved, you can click on the hyperlinked name in the description's view page to go to the authority record. Alternatively, you can navigate to Browse > Authority record and search or browse for your authority record there.
If you enter edit mode on the authority record, you will see a History field. Once you have added data here, the history will automatically display on the related archival description at the level where it is linked.
You can read more about this in our documentation here: