Bitcoin mining is the backbone of the Bitcoin network. ... Miners achieve this by solving a computational problem which allows them to chain together blocks of transactions (hence Bitcoin's famous “blockchain”). For this service, miners are rewarded with newly-created Bitcoins and transaction fees.
Keep reading....
https://www.bitcoinmining.com
https://www.economist.com/the-economist-explains/2015/01/20/how-bitcoin-mining-works
https://www.investopedia.com/tech/how-does-bitcoin-mining-work
https://www.coindesk.com/information/how-bitcoin-mining-works
https://www.buybitcoinworldwide.com/mining
http://www.cityam.com/277040/bitcoin-mining-explained-does-work-why-does-use-so-much
PS: No offence but you really need to read this post: Newbies - Read before posting
It's gonna help you to understand the forum a bit.