'Select' fields in form - problem with adding correct class

Hi everybody!

I have simply form in jQuery and I wanted to add more 'select fields'.
And I have little problem - I can't figure out how to use Class JUST ONLY AT ONE field - which is active (clicked). Now I have something like this: after click on each field, all fields are being active.
But it should be active (new Class) just for this element (field) which is clicked.
I tried to add "$this" in some part of code, but it still doesn't work... Any help?

Here is DEMO

• Topic Participants

• jtara-jquery

• kbwood.au