Use the left click button on the mouse to select a space on the grid. If you hit a bomb, you lose.
The numbers on the board represent how many bombs are adjacent to a square. For example, if a square has a "2" on it, then it means there are 2 bombs next to that square. The bombs could be above, below, right left, or diagonal to the square.
You can right click a square with the mouse to place a flag where you think a bomb is. This allows you to avoid that spot.
Avoid all the bombs and expose all the empty spaces to win Minesweeper.