Excel dropdowns

Hi there, I'm looking for someone to create a few dropdown lists in my excel spreadsheet, and let me know how to amend and copy so that I can add to them in future.

Column B has the item description, Column C has the cost per m2 - I need to be able to drop down on Column B to different options say of wood (pine / larch), which each have a different cost per m2. That's it really. I am just a complete Excel novice!

Thanks
Katie