You can use the Excel worksheet functions AVERAGE and STD to find the sample average and standard deviation, then use the function CONFIDENCE to find the width of a confidence interval. You can read about these functions in Excel's on-line help.
This is assuming that you want to find a confidence interval on the mean. But it may be, given your problem statement ("Older workers typically make more than younger workers"), that what you really want is a test of hypothesis. Have you thought about this?