Access 2000 — drop down boxes

I have a table with two columns (Reference,Name)
On a form I would like to have a drop down box to pick the Reference and another to show the Name based on this Reference(It(Name) does not need to be a drop down.

I would also like to be able to add items to a drop down list if they do not exist, my attempts at this do not seem to produce the required result even after consulting the help section.
I think I might need the NotInList statement in VB but am unsure how to wright the code.

CAN ANYONE HELP PLEASE ?????