Forecasting

hi there people,

i am looking for some sort of formula, where i can see the forecast of sales amount and the products quantity based on the following scenarios

1- based last 12 months trend
2- based on last 4 quarters

i want to create two forecasting trends i have a data of over the period of two years and have 150 products, please also advise me can i make graphs of the forecasting or not.

Thanks & Regards.

Usman

also the data is in raw form and connected to a pivot table which actually calculates the amount of sales and group the dates, is there any chance with relation to that pivot i can make another tab of forecasting which will forecast the amount of sales againt all the products from the next three months and a one quarter.