Open the Manage Database dialog - where you control the tables, fields and relationships.
Then in the relationships tab, double-click the relationship between Person and Event and it will open a new dialog that defines the relationship between the two tables. This dialog shows details of the relationship in two vertical halves - 1 for each table. At the bottom of the dialog there are several checkboxes. On the Event side, check "Allow creation of records through this relationship". Click O.K. to confirm the changes and click O.K. again on the Manage Database dialog.
Now the first blank row in the portal will represent a record that hasn't been created yet. Entering any field in this first blank row will, create a record in Events - related to the Person that is currently being viewed.