E-Mail notifications can be used to alert you based on the Backup Jobs behaviour/status. These notifications will run once a day, every day, looking for any backups that meet the programmed criteria.

Click on Email Notifications - Create a New Email Notification

Then you'll be presented with the following options:

Name

You'll be prompted to name the notification, best to choose one that is at least mildly descriptive especially if you create more than notification.

Subject

Backup Radar will automatically apply a subject to the email notification so you can leave this field blank. However if you wish to customize the subject, the question mark reveals a list of preset variables available to you.

Group Backups By

This feature allows you to group the issues, with the goal of reducing the overall number of email notifications sent without losing any information. The default choice is Backup, which will create an email for each individual issue whereas the other options (Company, Job Name, Device Name) can combine multiple issues onto a single email.

From

The default (and only) option is Backup Radar unless you were to configure custom email settings (Configuration E-mail Settings Configure New Email)

When

As stated above, this defines when the email notification rule will run daily. This means that when this runs at the set time (Select Time field) it will look at yesterday's results. 

What

Here's where you'll program what generates an email. Leaving a field empty will actually act as 'Select All' (ie, all Companies, all Backup Methods) and you only need to add selections to the field when you want to narrow down the focus (ie, selecting Failure under Status so that only a failure status can trigger the notification).