Greetings, guys can you help me with this error?

Warning: mail() [function.mail]: Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in C:\xampp\htdocs\email_verify\register.php on line 63

Apparently, no mail server installed on localhost.

where can i get a mail server sir?

If you are working in local system, mail function will not work due to SMTP.
Once you upload it on live server it will work as most live server have SMTP default set.

There are mail servers available. Search the PHP forum, I know it's mentioned somewhere.

in XAMPP, there is a build in mail system called mercury mail. if you want to use smpt, you need to get that info from yahoo, google.. unless your using outlook, then just use that info.