How do I compute/add an average to a line chart?

I have a set of data graphed on line charts (time on x-axis and value on y-axis). 

I would like to plot the time value along with either/or the moving average or an average over a specified period of time for each point in time.

Being new to MashZone, I believe my issue is in the data feed creation and manipulation of the averages and I can't seem to figure out what seems like a potential simple thing.  (I really do NOT want to have to do the math in Excel and bring in another data feed.)

Has anyone done this?  If so, please help.  ;-)

For extra credit, it would be great to set the conditional formatting (thresholds) for these charts based on the moving/time average value.

Thanks....