Other - Java script for populating dropdown list

hi i have a query in java script.(i am working in cold fusion. )

populate 2nd drop down values accordingly first drop down selection. can you provide me example code for this one. have used arrays in this.then i am facing problem when i click submit the value is not going to store.

Please post some code ( in code tags ).
So it's more clear what you try to achieve.

Léon