Bitcoin Mining

Mining for bit coin, this you have surely heard about. You've also heard that it requires massive amounts of computing power and therefore electricity. As of last year, bit coin mining consumed more than one half of one % of all global electricity production. So how does crypto mining work? And what's the point? Every ten at there's a new block of transactions added to the bitcon data base. But who gets to add those new rows to the spred heap? If anyone had access, there'd be nothing to stop a bad actor from manipulating the data in their favor. We couldn't trust the data base.