<style type="text/css">
submit {
	background-image:url(proceed.gif);
	background-repeat:no-repeat;
	width:146px;
	height:30px;
	border:none;
}
</style>

<?PHP
$textbox1 = $_POST['textbox1'];
$textbox2 = $_POST['textbox2'];
?>


<FORM ID="" ACTION="pagina2.php">
<label class="contact">Textbox1:</label>
<INPUT TYPE=TEXT class="textboxstyle" NAME="textbox1" MAXLENGTH=30><BR><BR>
<label class="contact">Textbox2:</label>
<INPUT TYPE=TEXT class="textboxstyle" NAME="textbox2" MAXLENGTH=40>
<br><br>
<INPUT TYPE=SUBMIT VALUE="" class="textboxstyle">
</FORM>

<style type="text/css">
.submit2 {
	background-image:url(proceed.gif);
	background-repeat:no-repeat;
	width:146px;
	height:30px;
	border:none;
}
.submit3 {
	background-image:url(back.gif);
	background-repeat:no-repeat;
	width:146px;
	height:30px;
	border:none;
}
</style>	

<?php
if (empty($textbox1)) {
echo "<h2>Sorry! Textbox1 should not be empty</h2><br>";
}
?>

<?php
if (empty($textbox2)) {
echo "<h2>Sorry! Textbox2 should not be empty</h2><br>";
}
?>


<?php
if (empty($textbox1) || (empty($textbox2))){
}
else{
echo "<h2>Your text is ok!</h2>";
}
?>


<br><br>

Please Check Your Text:
<?php
echo $_GET['textbox1'];
?>
<br>
Your Slogan:
<?php
echo $_GET['textbox2'];
?>

<br><br><br>

<a href="pagina1.php">
<?php
if (empty($textbox1) || (empty($textbox2))){
echo "<input type=button name=back class=submit3>";
}
else{
}
?>
</a>


<a href="paypal.php">
<?php
if (empty($textbox1) || (empty($textbox2))){
}
else{
echo "<input type=button name=proceed class=submit2>";
}
?>
</a>

<?php
session_start();
//--------------------------------------------------------------------------------------------//
// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';
$i = 0;
foreach ($_REQUEST as $key => $value) 
{
	$value = urlencode(stripslashes($value));
	$req .= "&$key=$value";
}

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('www.paypal.com', 80, $errno, $errstr, 30);

<form action="https://www.paypal.com/cgi-bin/webscr" method="post" name="paypal">
		<? $url=$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'];
			$url = "http://".substr($url,0,strlen($url)-11)."/"; ?>
					<? $url2="http://".$_SERVER['HTTP_HOST'];?>
 <input type="hidden" name="cmd" value="_cart">
 <input type="hidden" name="upload" value="1">
  <input type="hidden" name="business" value="xxx@xxx.xxx">
 <input type="hidden" name="currency_code" value="USD">
 <input type="hidden" name="custom" value="<?=$_REQUEST["textbox1"]?>">
 <input type="hidden" name="return" value="<?=$url?>succpaid.php" />
 <input type="hidden" name="notify_url" value="<?=$url?>success.php">
 <input type="hidden" name="cancel_return" value="<?=$url?>failure.php" />
 <input type="hidden" name="receiver_email" value="" />
 <input type="hidden" name="merchant_product_description" value="Photo Upload">
 <input type="hidden" name="item_name_1" value="<?=$item?>" />
 <input type="hidden" name="item_number_1" value="<?=$orderid?>" />
 <input type="hidden" name="quantity_1" value="1" />
 <input type="hidden" name="packageid_1" value="<?=$orderid?>" />
 <input type="hidden" name="amount_1" value="259" />
 </form>

bla bla bla...

<input type="submit" value="Submit" name='submit'>

$item_name = $_REQUEST['item_name_1'];
$item_number = $_REQUEST['quantity_1'];
$payment_amount = $_REQUEST['amount_1'];

$payment_status = $_REQUEST['payment_status'];
$payment_currency = $_REQUEST['mc_currency'];
$txn_id = $_REQUEST['txn_id'];
$receiver_email = $_REQUEST['receiver_email'];
$payer_email = $_REQUEST['payer_email'];
$customdata = $_REQUEST['custom'];

$listing_id = $_REQUEST['list_1'];
$subscription_id =$_REQUEST['item_number1'];
$email = $_REQUEST['payer_email'];


	 if($payment_status=="Completed")
	 {

Y acá le manda un mail al admin con el contenido de los 2 textbox entre otras cosas.

$customdata = $_REQUEST['custom'];