I'm confused how to do this. Please Help! I need to forecast what the last four quarters sales figures would have been expected to be, and then perform a MAPE analysis on my forecast. Details: Go to the Johnson & Johnsons investor relations sales and earnings page at www.investor.jnj.com/sales-earnings.cfm. Then download all available sales reports and set the last four quarters sales figures aside as an out-of-sample test group. Then use the rest of the worldwide historical sales figures to forecast what the last four quarters sales figures would have been expected to be, and then perform a MAPE analysis on my forecasts.

I'm a little lost on this assignment and my online teacher is not answering any questions or teaching us this material at all. And the book of course is leaving me confused as well. I just want to know how to do this