auto update the date edited on column

i have one share file, some range already fix the user to update the data. how can i show the data already updated by WHO and Date Updated on the top of the column.

for example:

<coloum a> <coloum b> <coloum c>
12/02/09 user a 13/02/09 user b 10/02/09 user c
data 1 data 2 data 3