hello Ammar, and welcome to PHPBuilder.
first question, do you have the <?php tags open? according to the error, you do.
in php, when your trying to show html inside the <?php tags, you have to use a command, such as echo or print, not just for variables, but for strings [ which includes html ]
<form action="" method="get">
<p>Username: <input type="text" name="user"/></p>
<p>Your address: <textarea name="address" rows="5" cols="40"></textarea></p>
<p><input type="submit" value="hit it!" /></p>
</form>
<?php
print "welcome <b>" . $_GET['user'] . "</b><br/>";
print "your address is: <b>" . $_GET['address'] . "</b>";
?>
http://nhassan.net/test/test4.php
one more thing to remember. when you open a <?php you have to close it