Excel entering data and using it

Guys,

I need your help, I need to know how I would do this, I want to enter a list of goods and how much we sell every £100 for example then enter the days projected sales and the sheet tell me how much I will sell for that day.

Any ideas, Please help.

Excel 2002, on WinXP

I've entered my data on sheet two, how do I use the figues on sheet one. i.e i want on sheet1 - sheet 2 B3* sheet 1 B2

How would I do this?