Only following code needs to be replaced with your custom html
<html>
<head>
<title>Please enter password to access this page</title>
<META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE">
<META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">
</head>
<body>
<style>
input { border: 1px solid black; }
</style>
<div style="width:500px; margin-left:auto; margin-right:auto; text-align:center">
<form method="post">
<h3>Please enter password to access this page</h3>
<font color="red"><?php echo $error_msg; ?></font><br />
<?php if (USE_USERNAME) echo 'Login:<br /><input type="input" name="access_login" /><br />Password:<br />'; ?>
<input type="password" name="access_password" /><p></p><input type="submit" name="Submit" value="Submit" />
</form>
<br />
<a style="font-size:9px; color: #B0B0B0; font-family: Verdana, Arial;" href="http://www.zubrag.com/scripts/password-protect.php" title="Download Password Protector">Powered by Password Protect</a>
</div>
</body>
</html>
and this code needs to be placed in your custom html where you want login form
<form method="post">
<font color="red"><?php echo $error_msg; ?></font><br />
<?php if (USE_USERNAME) echo 'Login:<br /><input type="input" name="access_login" /><br />Password:<br />'; ?>
<input type="password" name="access_password" /><p></p><input type="submit" name="Submit" value="Submit" />
</form>