How To Print Values From A Php File

I am using change_order_status_post hook. With this hook I get a variable $order_info. How can I see what this variable return? I try to echo it but it does not show anywhere. I know for sure that my function is called. Is there any way to log the value to $order_info?

And another question, why I cannot post in Developer's Corner section?

For example, you can use the following code

file_put_contents('order_info.txt', var_export($order_info, true), FILE_APPEND);

After the function is called, the order_info.txt file will be created in the root directory of CS-Cart installation with the required information

Or in the template use a comment such as:

The just search the page source for MY_UNIQUE_MARKER.