Need Help on creating LISTS using Helper classes

I am new to ruby on rails and doing a simple application as I am
studying ruby on rails.

I have a m:n relationship between people and languages …
a person can know many langs and a lang can be known by many people …

I want to give a GUI in which there are 2 lists of languages for a
person to edit
1 with the languages he knows
2 other languages …

I want to allow him to add & remove languages ie shift from one list to
the other list

Eg: if person1 has english and french in the database , the lists would
look like

List1 : List2
english spanish
french italian
etc etc etc…

and he can double click or do something to select a lang in list2 and
add it to list1 and vice versa…

I thought it would be a good excerise to learn ruby but I am struck …
I wanted to know if there is any helper class available for this kinda

Can someone suggest me as to how I can do this efficiently in ruby…
[ I currently have a string which has all languages seperated by comma
and the user can modify the string… I parse the string @ the
controller and store it into the database… ]