Excel Autopopulate Help needed

Hi!
I need help in developing an excel formula to auto populate a range of cells with the chosen criteria (from a drop-down list).

I.e. Upon selecting the critieria from Cell B2 (product name), Cell from B9 to B19 will auto populate the list of customer who buy this product.

see attached worksheet for a clearer picture of what I need here....

Thanks for guiding me in solving this one...