You'll need to use an Advanced alert to set this up, here's the general steps:
1) You'll need to identify an existing VizAlerts schedule, of if necessary a Tableau Server admin will need to create the VizAlerts schedule to run on. This is covered in the VizAlerts install guide.
2) Set up a data source (database, text file, Excel file, etc.) with the list of recipients (what will be the Email To field for the alert) and potentially some amount of additional fields required for VizAlerts e.g. Email From, Email Subject, Email Body, etc.
3) Create a Tableau visualization (called the trigger view in VizAlerts terminology) using that data source that has all the required VizAlerts fields in the view (where some of those fields might be from step #2 or from calculated fields that you create). Usually I just use a text table for this since it lets me see & validate all the values. The Email Body and/or Email Attachment fields will use content references to include the image, PDF, and/or CSV of the dashboard. See the VizAlerts User Guide for specific instructions. Also the VizAlerts demo workbook that was installed as part of the installation & configuration of VizAlerts has examples that you can use.
4) Publish the trigger view.
5) Subscribe the trigger view to the schedule from step 1.
Hope this helps!