Drop Down for Announce List

I’m trying to create a dropdown list for the announce list signup. Instead of “Subscribe” and “Unsubscribe” buttons, I want to have a dropdown list with “Subscribe” and “Unsubscribe” as the options, then a button that says “Submit.” I know a little bit about javaScript, but I haven’t been able to figure out how to send the “unsub” value data to the DH script. Anyone have any suggestions. Thanks!