I want to know how this site(phphelp.com) built how login and log out, how new topic received and the structer of mysql and all php files.
Try this script: http://www.phpbb.com/
I don’t think you searched Google or put ANY kind of effort at all into finding the answers to your question. And let that just be what we expect on this forum. Yes, phpBB is opensource, so you can view the code and learn all you want. But we won’t hold your hand while you do, that’s not our job.