Now your Rule has been created then you can specify what Actions are to take place when the Rule is triggered.  In the Action tab press [New] to launch the Action pop up.

Select Type - this will display all the current actions available, select 'Add Notification' and the field to the right will update its label based on the Type you have selected.

Fig 1 - Notification selection

The Recipient field drop down will display all the Users in your account, you can select as many People as you wish to be notified.  You can use the magnifying glass icon next to the drop down list to open up the Find screen, this will show all the Users with additional details such as email address.

Once the Recipients are selected press [Save] the Action will now be added to your Rule.

Notifications are sent to the email address of the Users selected, the content of the email by default will contain the account name, the User name and the Action Note.

Fig 2 - Email Notification

If you wish to change the format of the email notification other than the Action Note then you will need to update the Notification template.  Please refer to this article for more information about updating Notification Templates

The template concerned is the Type 'Automation has been completed', as highlighted below. 

Fig 3 - Template Types

Notification is also sent to the Notification area on the top right of the screen.

Fig 4 - Notification information

Multiple Actions

If you wish to trigger multiple Actions for your Rule, click the new button again and add a new Action.  You can add as many different Actions as you wish. 

When you create a new record or edit an existing one that is within the Criteria of a Rule, the Actions will be automatically created when the record is [Saved].