Usually, you do not need to create aggregate Snapshot copies manually. A schedule is automatically set up to generate new aggregate Snapshot copies periodically. In most cases, you should not need to change the aggregate Snapshot copy schedule.
If you do need to create an aggregate Snapshot copy manually, you use the same command as you would for a volume Snapshot copy, except that you add the -A flag. For more information on creating Snapshot copies, see the Data ONTAP Data Protection Online Backup and Recovery Guide.