How to play Sudoku 3x3

There is really only one rule:

• Fill in the grid so that
• every row,
• every column, and
• every 3 x 3 box
• contains the digits 1 through 9.

What is Sudoku: rules, history and terminology

This Puzzlue Address: http://sudoku.oubk.com/puzzles/5763986672.html to a friend to play together