As mocacinno said you can't mine bitcoin but you can mine certain altcoins with your GPU, you can read topics in the altcoin mining board: https://bitcointalk.org/index.php?board=160.0 or ask your questions there.
Generally speaking you need to have a low electricity price, a decent GPU that can give you a decent hashrate and then you just find the most profitable altcoin to mine and sell your rewards for bitcoin or fiat.
There are some calculators that can help you decide too. Like this site: https://whattomine.com/