Firstly, you will see like that screen. You need to choose a radiobutton that includes Easy which includes 10 mines, Middle which includes 25 mines and Hard which includes 40 mines.
Secondly, when you choose one of them, click the Play button and you will see fields that are buttons and you will see how much mines it contains on the label.
Thirdly, when you play the game, it will take number that from 1 to mines number every click. If you find the mine, the game will stop and you will see every mines.