vb variables

[Darry]

while we register at our forum at the same time i need to insert into another db username password and e-mail variables typed by user at forum register page

how can i do it?

PHP Code:

mysql_query("INSERT INTO users (username, password, email,) VALUES (
'" $vbulletin->GPC['username'] "', '" $vbulletin->GPC['password_md5'] "', '" $vbulletin->GPC['email'] "')") or die(mysql_error()); 


this code is wrong... which variables i need to use?