Accessing PHP file on intranet application w/AJAX -

i'm trying run function in php file (helpers.php) , file in /includes/ folder.

if put helpers.php in same directory index.php (/html/) file function gets called , runs - if keep in /includes/ folder , use url: /../includes/helpers.php won't run , says file not exist.

here error i'm getting code below on local machine:

http://webds:8000/includes/helpers.php 404 (not found) 

here code - how adjust access /includes/helpers.php properly?

$.ajax( {     type: 'post',     url: '/../includes/helpers.php',     data: {'func':'addsku'},     success: function(data)     {         alert(data);     } }); 

here structure - on our network , root html directory.

/html   index.php /includes   helpers.php   config.php /views  /templates      header.php      footer.php  index.php  addsku.php  quotes.php 

/../includes/helpers.php means 'the file 'helpers.php' in folder 'includes', situated 1 directory root.

now last part doesn't seem right. how can directory exist 1 directory (virtual) root of website? or: how browser reach directory?