Make sure you understand the concept of Creating Custom APIs Using Logics and then continue reading here.
Take these steps:
Navigate to the “API” API tab of the logic editor.
The API tester console calls the logic on the server. Therefore if you do not have your logic deployed on the partition yet, select the “Deploy logic” Deploy logic checkbox. It will deploy the logic to the partition selected at the top of the editor.
If you want to generate the JSON payload using the parameter values from the “Parameters” Parameters tab, select “Payload Payload from Parameters“ Parameters checkbox. Deselect this option if you want to provide the payload manually and the “Request payload” Request Payload tab will become editable.
Click the Run button and you can check the endpoint response in the “Response body” Response Body tab.
If you want to copy the endpoint URL to the clipboard, e.g. to send it to the customer, click the “Copy” Copy button next to the endpoint URL.