seasonality-example.xlsx

Hi guys, I have a record of daily sales numbers for 3 products and from charting it, I can see seasonal/weekly-cycle effects. If I had a proper statistical package, I will:

1) Separate the data into 21 groups: {Eclairs, Donuts, Muffins} and {Mon, Tue, Wed, Thu, Fri, Sat, Sun}
2) Calculate the regression trendlines for the 21 groups.
3) Detrend the data by subtracting the actual data from the regression trendline from the previous step
4) Average the residuals from the previous step for each of the 21 groups
5) Average the residuals for {Eclairs, Donuts, Muffins}
6) Calculate the "seasonal"/weekly index by dividing results of step4/step5
7) Perform an appropriate non-parametric test.

I need help on implementing steps 1-5 on excel! Can I do this using functions or do I need to write a VBA macro to do this?