post - why can't Codeigniterload Input class, and can't find the file either -

I'm trying to use the postigniters input class, to use the post method. Now, I tried to load it into the controller and the auto loader, but no luck! Error is occurring

  Unable to load the requested file: helpers / input_helper.php   
 looking through my code and trying to find it After the input but for the IDE nothing could be found. I essentially  
  $ this-> Input-> I want to use the post ('varname');   
 Nothing crazy, is this file not included by coding by default? I have got the most recent release from Github a few days ago. If I say something stupid, please be very new to codeigniter, please forgive me an explanation will be greatly appreciated!   
 
 
 You do not need to load this assistant at all:  
 < P> Note: This class is automatically started by the system, so there is no need to do it manually.   
 Try removing your efforts to auto-load in the administrator or elsewhere, then try again and see if that works.