How to set namespace correct in PHP? -

i have load file index.php in server in directory public_html. in file set namespace , use as:

namespace public_html;  error_reporting(e_all); ini_set('memory_limit', '-1');  set_time_limit(0);  use public_html\helper\curl\curlheaders; use public_html\helper\curl\curl curl; use public_html\helper\pdo\facadequery db; 

so, files see located in root directory public_html

when run script error:

fatal error: class 'public_html\helper\pdo\facadequery' not found in /home/bulud/public_html/parse.php on line 34