Apache Friends Support Forum

sir....why i cannot open http://localhost/phpBB3/instal/index.php

How can we possibly know?

Check the error log file in C:\xampp\apache\logs\error.log

My guess is that you typed the wrong address in your browser:
http://localhost/phpBB3/install/index.php might get you there - should be install not instal

Also make sure the folder is phpBB3 and not phpbb3 - apache is case sensitive.