I Have Found the ANSWER (Of course, without any of your help, guys, thanks for nothing ;-)
So, If anybody is interested, this problem has a dual-solving component:
First of all, the administrator of the server where the site is hosted must configure the httpd.conf to accept wildcard dns.
Then, u must write some code into the .htaccess file.
The code is as follows:
Code:
#start of code
Options +FollowSymLinks
RewriteEngine on
RewriteBase /
RewriteCond %{HTTP_HOST} ^www\.([^.]+)\.yoursite\.com$ [NC]
RewriteRule ^$ http://www.yoursite.com/dinamicpage.php?value=%1 [L]
#end of code
So if u want to have
http://www.username.yoursite.com as a virtual subdomain redirect to yoursite.com/a-page.php?user=username, u must:
1. contact your admin host (the firm that is hosting your site) and ask them to allow you to have virtual subdomains (they must allow you to have wildcard dns, this is a setting that must be done in the httpd.conf file on the server)
2. write the code above inside the .htaccess file
Hope this post will help many users.
John.