?B?QXJsZW4=?= wrote

For instance, if all the workdays for a month are listed in column A,
is it possible to look up all the Fridays and change the corresponding
cell in Column C from whatever color to Yellow?

You could use Conditional Formatting (you would have to Unprotect the sheet
first):
Say dates in A start at A2
Select all corresponding cells in C
Format|Conditional Formatting
Formula Is|=Weekday(A2)=6
Format|Patterns and pick Yellow

--
David