Determining dates based on colored cells.

I'm using Excel 2000.

What I'm trying to do is as follows:

Lets say I have a row of numbers that are fiscal weeks like this,

1 2 3 4 5 6 7 8 9 10

and i have a row of empty boxes underneath them, which when changed to the
color green, i want seperate cells to give the start and end dates of those
fiscal weeks. How would I link the fiscal numbers to dates? and what kind of
if-then statement would I need for it to calculate a time span? for example:

green boxes under fiscal weeks 5 to 7
1 2 3 4 5 6 7 8 9 10
[g][g][g]

then have two seperate cells, containing the calculated Start date, and the
other with end date. i'd imagine linking the fiscal numbers to real dates
would allow excel to add and subtract them.

if it's too complex to be answered i understand, thanks

ej