Hi guys i want know, why i see on gametrakcer only player online, but i dont see the stats of the top 10. I mean the player ranking whit score, minutes played ecc

If you are referring to the server in your 'Favourites'; player statistics are not tracked when the server page is not claimed.

It says this on the server page under 'TOP 10 PLAYERS'

How does it work? Is a paid service if you pay as you pay per month?

Gametracker is completely free.

But Gametracker does not own, run or rent any servers. We simply track statistics and rank servers accordingly.

The server will be owned / rented by a private individual who may not even know that it is registered here.

One option for renting game servers is; https://www.gameservers.com/game_servers/

You can search for active, privately owned / rented servers, registered on this site, using this link; https://www.gametracker.com/servers/

Thank you for you answer, but To activate the ranking of my server players cod 4 am I paying something? How do you do it?

No charge.
You take ownership of the server / server page;
https://www.gametracker.com/forums/forum.php?site=1&thread=108252

Nearly every question one might ask is answered in the FAQs
https://www.gametracker.com/forums/forum.php?site=1&category=173713