<form method=post action=register.php?action=register  name=s>
<table>
<tr><td>Username:</td><td><input type=text name=user></td></tr>
<tr><td>Email:</td><td><input type=text name=email></td></tr>
<tr><td>Pass:</td><td><input type=password name=pass></td></tr>
<tr><td>Verify Pass:</td><td><input type=password name=vpass></td></tr>
<tr><td colspan=2 align=center><input type=submit value=Register></td></tr>
</table>
</form>
<?php

//Login to your database. Make the fields of course..
mysql_connect("localhost","user","pass");
mysql_select_db("database");
//end

//if registering, check fields.
if ($action == register) {

if (!$user || !$pass || !$email || !$vpass) {
 print "You must fill out all fields.";

 exit;
}
$dupe1 = mysql_num_rows(mysql_query("select * from table where user='$user'"));

if ($dupe1 > 0) {
 print "Someone already has that username.";

 exit;
}
$dupe2 = mysql_num_rows(mysql_query("select * from table where email='$email'"));
if ($dupe2 > 0) {
 print "Someone already has that email.";

 exit;
}

//check if passwords are the same
if ($pass != $vpass) {
 print "The passwords do not match.";

 exit;
}
//end
//insert
mysql_query("insert into table (user, email, pass) values('$user','$email','$pass')");
print "You are now registered. Login.";
}
?>

<form method=post action=Login.php?action=login>
<table>
<tr><td>Email:</td><td><input type=text name=email></td></tr>
<tr><td>Pass:</td><td><input type=password name=pass></td></tr>
<tr><td colspan=2 align=center><input type=submit value=Login></td></tr>
</form>
</table>
<?php
if($action==login){
//check
if (!$email || !$pass) {
print "Please fill out all fields.";

exit;
}
$logres = mysql_num_rows(mysql_query("select * from table where user='$email' and pass='$pass'"));
if ($logres <= 0) {
print "Login failed. If you have not already, please signup. Otherwise, check your spelling and login again.";

exit;
} else {
//logged in, register the session..
session_register("email");
session_register("pass");
print "You are now logged in..";
}
}
?>

<?php
if (!session_is_registered("email") || !session_is_registered("pass")) {
print "You need to login to view this page!! ";
exit;
}
print "Content here";
?>

CREATE TABLE `table` (
 `id` int(5) NOT NULL auto_increment,
 `user` varchar(255) NOT NULL default '',
 `email` varchar(255) NOT NULL default '',
 `pass` varchar(255) NOT NULL default '',
 PRIMARY KEY  (`id`)
) TYPE=MyISAM AUTO_INCREMENT=1;