I mean , to generate the block all I need is to find a number that is lower than a target ,
what if you will find the same number in the same time or nearby and will claim the ownership
on the money in the block.
oh now i understand! they can't find the same block, with the same hash(yes they can but its very very unlikely.). because the ownership of the reward, is a transaction in the block. that transaction is used to build the merkel tree, along with all the others transactions. and that merkel root will be included in the block, and it will change the hash of the block.
that why you also not can steal others blocks, if you tryed to put in a fake reward transaction, the block hash would change, and thereby invalidating the block.
for another time, please specify in the first post please, we can't understand you otherwise.