To receive notifications about the hosts you monitor:
Create a rule.
In the rule, specify for which host check results a notification should be sent.
In the rule, also specify what should happen when the conditions from the previous step are met - for example, an alert can be raised.
Create also a recipient, for which you define the media (like e-mail or Slack) and address to which notifications should be sent.
That's all. CloudRadar provides by default a set of common rules, which cover the most common monitoring cases. If needed, you can define your own rules, for example for a particular host.