如何在CodeIgniter中使用Captcha插件

I followed this page, and the code is not working as it should in my project. I've tried to find other tutorial on how to execute what I need, however, it does not work as it should in my project either. Is anyone able to direct me to a tutorial that explains in a detailed fashion on how to use Captcha plug-in properly in CodeIgniter? , and the code is not worki