vn412 0 Light Poster

Hi, I've problem with formatting the data. I have rows in grid with date columns "1-12-2011, 7-6-2011, 06-12-2010, 07-12-2010, 08-12-2010, 09-12-2010, 10-12-2010" similary in other rows i have the values like this.
I need help with the code so that format the datatable as
Jan: values of dates in Jan
Feb: values of dates in Jan
etc
for each row in date column.

Please help.

Thanks