Step 1: Create a new Incoming Webhook in Slack

You can find more information about how to do that on the Slack website

Step 2: Extract your WebHook URL

On your newly created incoming Webhook, you will be given a Webhook URL that you need to copy.

Step 3: Activate Slack Add-on in PayTraq

Go to My PayTraq -> My Company -> Add-ons

Select Slack and paste Webhook URL you have copied.