You are making it hard for us to help you better. "It is not working the desired way" does not tell us anything about how the code from the linked article fails for you. Please show the relevant code of your program, your input and the output you get.

Ajax is still simple HTTP interaction, so writing an "Ajax script" is not different from writing any other CGI script, except that the output is JSON or some other format than HTML, and that the requesting client is likely driven by a JavaScript program.