Annoations are the first field you will see when you create the Constituent Mapping. Like all other fields, you can either map it to a field within your data source or add a default value.
When you map to this field, it will add or update the Annotation field in Raiser's Edge.
It is worth noting this will overwrite any existing Annotations that exist on the record in Raiser's Edge.
You can also update the where the Annotation will automatically displayed or not.