How to play Sudoku 3x4

There is really only one rule:

• Fill in the grid so that
• every row,
• every column, and
• every 3 x 4 box
• contains the digits 1 through 9 and a,b,c.

What is Sudoku: rules, history and terminology

This Puzzlue Address: http://sudoku.oubk.com/puzzles/6890395886.html to a friend to play together