Alright, let's get started with Supabase and Zapier. First things first, we need to create an API on Supabase. Here's how you do it:

• Log into your Supabase account.
• Click on 'new project'.
• Follow the steps to set up your database and API credentials.

Once your API is up and running, jot down your Supabase URL and Supabase Service Role Key. Trust me, you'll need these for the Zapier integration.

• Log into your Zapier account, or create a new one if you haven't already.
• Click on 'Create Zap'.

Now, we need something to kick off the process. That's where the 'Trigger App' comes in. For this example, we'll use 'Webhooks by Zapier'.

• Click on 'Webhooks by Zapier' and then 'Catch Hook'.
• Hit the 'Continue' button. Zapier will give you a 'Custom Webhook URL'.

• Head back to your Supabase project and add a new function by clicking SQL in the left sidebar.
• Create a new function that makes a POST request to your Webhook URL when the trigger event happens. Here's a sample code:

CREATE OR REPLACE FUNCTION new_order_webhook() RETURNS trigger AS $$
DECLARE
  payload json;
BEGIN
  payload = json_build_object(
    'id', NEW.id,
    'amount', NEW.amount,
    'created_at', NEW.created_at,
    -- add more data here
  );
  PERFORM pg_notify('webhook', 
    json_build_object(
      'url', 'https://hooks.zapier.com/your-webhook-url',
      'payload', payload,
      'method', 'POST',
      'headers', json_build_object(
        'apikey', 'your-supabase-service-role-key',
        'Content-Type', 'application/json'
      )
    )::text
  );
  RETURN NEW;
END; $$ LANGUAGE plpgsql;

This function should be called when a new order is placed.

CREATE TRIGGER new_order AFTER INSERT ON orders FOR EACH ROW EXECUTE PROCEDURE new_order_webhook();

So, whenever a new order is created, the new_order_webhook function will send a POST request to the Webhook URL provided by Zapier.

Now that Zapier is getting the POST request, let's define what happens next.

• After setting up the Trigger, click on 'Continue' to set up the Action.
• Choose the platform where you want to take action and fill in the required information.
• Finally, test your Zap to make sure everything is working as expected. If all is good, turn on your Zap.

And there you have it! Now, every time a new order is placed in Supabase, the zap will trigger the action in the chosen platform.