I studied and learned that bitcoin network doesn't create new coins. The coins that miners earn are paid by users. As 1+1=2, there is no new money on the system after that. Am I correct ?
So, that is my question: when had the first Bitcoin amount been created ? Is that in Ground Zero Block ?
Today the system have the same amount of Bitcoin of two years ago ?
This is not true, I believe you're confusing some characteristics of the finite money supply Bitcoin will have.
Bitcoin has a maximum amount of coins that can be created, however not all of those coins have been created or unlocked yet, it requires transactions (and therefore mining) to unlock more coins each day, week, month. The bitcoin protocol has determined that no more than 21 million bitcoins will be available to be mined. It's possible that not all coins will be mined.
The coins miners earn are a combination of newly minted/mined coins and fees paid by the person initiating the transaction. The first block would have been created in 2009 by Satoshi. I don't know exactly how but I would presume Satoshi started off with some coins to use for transactions and get this whole blockchain-based system operational.
Today there are more coins in existence than there were two years ago, due to the mining that has occurred and will continue to occur. A great site to see the growth of bitcoin money supply is from the charts at Blockchain.info, find it here:
https://blockchain.info/charts/total-bi ... pan=2years