Here are some things, you should know about minesweeper.
1. The game completes when you have opened all the safe blocks not when you've flagged every mine.
2. If you accidentally click on a mine, just keep your mouse button held down and slide your cursor.
3. Start from the middle, you've a higher chance to get stuck if you start from the side.
4. If you are forced to guess, make the guess which has the least risk.
5. If you don't know all the moves, then trying to go faster actually makes you worse. So go slow.
6. If you are forced to guess, make a guess that will actually help you if it turns out to be right.
7. Don't just choose the first valid move you notice, choose the best move available.
8. Don't mark a mine if it can't possibly help you figure out the clear squares.
9. You can change the settings and difficulty:
And now you know it.