suppose data is there from A2 down
click format(menu bar)-conditional formatting
in that window
under condition 1
"the formula is "
in the right hand side window type
click format in the middle row of this window
in the format cells window
click "pattern" the last item at the top
choose a color
again click ok
now again select A1 -edit-copy
select A3 down and edit-pastespecial-format
some dates will be in that color and those rows are relevant
dates more than 13 days will be in red.