warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\Project_B5\expert_reg.php:1) in C:\xampp\htdocs\Project_B5\expert_reg.php on line 88 code example

Example: Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\heermatka\myprofile.php:48) in C:\xampp\htdocs\heermatka\myprofile.php on line 144

ob_start();
Please paste top on the page.