i am a novice, but i do no one way to do it. create a 'list' of options to
appear in dropdown box, say, on sheets 'list sheet' (or on same sheet) in
cells a1:c1 that contains 'yes', 'no', and 'na'.
then, select the cell(s) that you want the drop box in, hit 'data',
'validation', under 'allow' area, choose 'list' and under 'source' select
cells a1:c1 on 'list sheet'. you can then go to the next tab and type in
instructions to be shown on the box, etc.
you can also name the list and refer to it under this name like a named
range. hope this helps. mike allen