How to add tasks, events, calls to a contact record?
To add activities
1. Open the Bigin app on your iPhone.
2. Navigate to the Contacts 
module.
3. Select the desired contact record.
4. Tap the Add 
icon at the top right of the screen.
5. Select the relevant option from the dropdown.
To view activities related to a contact
1. Select the desired contact record.
2. Switch to the Related tab.
The list of open and closed activities of the contact can be found here.