You will first need to verify each endpoint you wish to have with code that captures the header parameter X-Hook-Secret and then sends it back to IS.
Once having done this, IS will automatically send data to that endpoint that is registered and it will be up to you at that point what you wish to do with that information from there.
Documentation does not specify this registration requirement yet but the rest you need to know about verifying the endpoint can be found here:
https://developer.infusionsoft.com/docs/rest/#!/Rest_Hooks/createHookUsingPOST