how to use mcrypt_generic

Hello,

anyone can show me an example to encrypt a
text variable $text using mcrypt_generic ?

Suppose I have
$ text ="hello world";
and my key is
$key ="my secret key";

What I have to do to EN-crypt $text using the key above ,
and then what to do to DE-crypt it using the key above ?

There is no example on php.net ...also on this forum I cannot
find a lot of help , any help will be appreciated

thanks a lot !

ok I found solution here