i can't understand how the miners choose the transactions for example in this picture, the two first transactions have the same gas price why he didn't pick the second one first? does each miner have his own select mechanism (priority, gas price , gas limit, account,..)? what i can do if i want the second transaction to be validate first? do i have to raise the gas price or the gas limit?
Nobody can force a miner to do anything specific. Miners are free to do whatever they want and include whichever transactions they want - within certain parameters (for example block gas limit).
But the reason most miners choose to include transactions with high gas price is monetary incentive. They get more rewards for including transactions with high gas price so they naturally prefer those.
The only thing you can do to get your own transaction mined faster is to increase the gas price. The gas limit only influences whether the transaction is successful or not, whether it runs out of gas or not. Of course you have to think of the big picture as well so it doesn't help much to use high gas price, get your transaction mined fast and only realize your gas limit was too low and the transaction failed because of that.