API form submission - retrieve & use response status on website (callback)

API form submission - retrieve & use response status on website (callback)

We have a html/php form on our website that submits data to our creator app via the  https://creator.zoho.com/api/xml/write API URL.

When the form is submitted, we want to retrieve the status response from the Zoho app and use it on the website i.e. 

"Success" 
or  
"Failure, enter a valid..." 

I can't find any documentation on this, can anybody share the simplest way to do it.

Many thanks