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When you create a new Calendar Appointment there is a section that allows you to create a "Reminder", these function as alerts. You can choose to set up any number of Alerts. Simply click the Add Reminder button then use the drop down to choose one from the time frame that you would like the alert to go off. Now tick the box next to how you would like to be alerted. You can choose to be alerted in more than one way.
To learn how to setup your system for SMS alerts have a look at our user guide here: SMS/TXT Alerts Setup
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Before you create an alert you will first need to create a default task.
Then from your default task list you will need to select the "alerts" icon that corresponds with you're chosen task. 
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From this screen you can specify the party your alert is assigned to, when it should appear, and in what form it should appear.
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