Once you open the Automation tab and click on "New Automation campaign", you will have to follow the steps described below:
Step 1: Setting your trigger
The trigger for it is “Places an order”.
“Filter by parameter of the triggering event”: equal to 1.
Step 2: Creating the email flow
Write your message in the composer or load a saved template. You can make it a sequence - timing is set from drop-downs for each message separately.