How do you cheat at minesweeper

First you need to enter the cheatcode:
1). Put your cursor inside the Minesweeper window
2). Type xyzzy
3). Press Shift-Enter and then Enter

Now a white dot will appear in the top-left corner of your screen. When you place your cursor over a square in Minesweeper the dot will turn black if the square is a mine.

Hope this helps. :)