如何在我的链接en php中重定向页面

I'm new programmer en PHP I would like to redirect the page

when I select the link but I don't know what i'm doing wrong because when i select the link i can't see the content of the page but the path of the browser it a true path.

this is my link:

<li><a href="category.php?catid=1">Literat</a></li>

but when i put

echo $_GET['catid'];  #en my page category.php  i don't see anything#

the page is empty.

i don't know how to make it work?

thank you very much

You try:

Create php file test with name test_get.php with content:

<?php
   error_reporting(E_ALL); 
   echo("First name: " . $_GET['firstname'] . "<br />
");
   echo("Last name: " . $_GET['lastname'] . "<br />
");
?>

Upload to your host and fill address like below:

http://your_host_domain/test_get.php?firstname=VNLIVES&lastname=.NET

If success you will see:

enter image description here

Else you see error report form PHP server.

Reference: http://www.html-form-guide.com/php-form/php-form-get.html

Good Luck!