Can anyone point me in the right direction to get some help?

I have a spreadsheet that is used to track financcial data. Currenlty you
type in the type of expense in two columns (eg: "gasoline" and "car 1" or
"phone" and "mobile #1". I have catagorised every type of expense broken down
into groups using a three part number (eg 11.14.02). Can I put a
formula/function/something in that allows me to choose off a small list in
column 1 (eg. showing "11 - Car expenses" and putting "11" in the box) which
then gives a different clist to choose off in colujmn two depending on what I
chose in column 1 (eg. showing "14 - gasoline" and putting 14 in the cell)
and the same for the third column? So what happens is you get a different
drop down list (with about 6 choices each) depending on what you chose in the
previous column.