<form id="frmLogin" method="post" action="chkauth.php">
    <table>
        <tr><td colspan="2" class="CenterAlign PostTitle"><p>Administrator Login</p></td></tr>
    <tr><td colspan="2">Please log in with your administrator username and password</td></tr>
    <tr><td>&nbsp;</td></tr>
    <tr>
        <td>Username:</td>
            <td><input id="adminname"type="text" /></td>
    </tr>
    <tr>
         <td>Password:</td>
         <td><input id="adminpass" type="password" /></td>
    </tr>
    <tr>
        <td colspan="2"><?php echo($message); ?></td>
        <td class="RightAlign"><input id="btnLogIn" type="submit" value="Log In" /></td>
    </tr>
    </table>
</form>

// chkauth.php
<?php
    // Set database server access variables:
    $host = "localhost";
    $user = "root";
    $pass = "root";
    $db = "logansarchive";

    // Open connection
    $connection = mysql_connect($host, $user, $pass) or die ("Unable to connect!");

    // Select database
    mysql_select_db($db) or die ("Unable to select database!");

    $user = $_POST["adminname"];
    $pass = $_POST["adminpass"];

        // Hash the password input
    $passwordHash = sha1(pass);
        // The database field only allows 20 characters, truncate the hash
    $passwordHash = substr(sha1($pass,0,20);

    $query = "SELECT AdminName FROM Admins WHERE AdminName = '".$user."' AND AdminPass = '".$passwordHash."'";
    $result = mysql_query($query) or die ("<p>Error in query:</p><p>".$query."</p><p>".mysql_error()."</p>");
    if (mysql_num_rows($result) < 1)
    {
        // Access denied
        header('Location: auth.php?r=0');
    }
    else
    {
        // Access granted
        session_start();
        $_SESSION['name'] = $user;
        header('Location: index.php');
    }
?>