First you find a common denominator, which is 12 ( as 4,3 and 6 all go into 12). So 2/4 becomes 6/12, as 4 multiplied by 3 is 12 and whatever you do to the denominator you must do to the numerator. Then 2/3 becomes 8/12. And 2/6 becomes 4/12. If you put these in order the answer is:
2/6, 2/4, 2/3