Please help using Excel

a$.$ Graph the time series data. What do you observe?

b$.$ Compute all possible forecasts using exponential smoothing with a smoothing coefficient $($a$)$ of $0\mathrm{.}3.$

c$.$ Compute all possible forecasts using exponential smoothing with a smoothing coefficient $($a$)$ of $0\mathrm{.}7.$

d$.$ Compute the MADs for each forecast model.

e$.$ Which forecast model would you choose? Why?