You can edit a response by selecting 'View Responses' and clicking the edit icon next to the person's name.
To add a response, go to Manage Events and click the options menu. You can add a response in two ways:
1. Select 'Add a Response' and you will see the same form your recipients see and you can complete it for them.
2. Select 'Invitation List' and click the 'Add Response' tab.