
First method is buy visiting the website
And just start mining with a free plan once you put you wallet address and make a passcode from your choice.
Second method is by using the Bitcoin mining browser
Which also givs you the chance to start mining for free. Of course because it is for free it will seem little bit slowly in the begining but after you have enough plan e you can withdraw the money, or you can request for a paid plan where the mining can be much faster.