If you are very lazy or it's too complicated then just download the Nicehash software and it will do it all for you and pay you directly in BTC.
This can be a very good option for beginners, but the downside is that Nicehash has a minimum minimum threshold for their payouts. You would have to wait some time (depending on your hardware) for the BTC to be accumulated and sent to an address you control.
If you don't want to wait, as others said, you simply go to
https://whattomine.com/ or
https://www.crypto-coinz.net/crypto-calculator/ or
https://www.coinwarz.com/cryptocurrency or some other similar online service.
You enter your GPU model or the hash-rate of your GPU for the selected algorithms, and you have a clear picture what to mine.