I need some advice on how to build a worksheet that references a previous
sheet and adds a value based on user input.

Example:

On sheet 1 I have the data in 2 columns. Each column has 20 rows of data.

Sheet 1
Column A Column B
1 5
2 12
3 9
Etc......

On sheet 2 I have 3 columns. The user will enter a value from Column A on
sheet 1 then will enter a quanity in Column 2 on sheet 2. In column 3 on
sheet 2 will be the quanity in colum B on sheet 2 multiplied by the data from
Column B on Sheet 1.

Sheet 2

Column 1 Column 2 Column 3
(user enters (user enters Coumn 2
value from quanity) times column B
Column A on
Sheet 1)

I think I probably made that confusing, but thanks for any help you can give.

Vachoen