Change the name of a card

[Scott Pepperdine]

Probably very simple to do.

I've got a field that is part of a background group, and so will be on 
every new card created in this stack.

I want to change the name of the card to the contents of this field 
after the user has typed something into the field.

So I presume the script for the field would start with "On Closefield", 
but then how do I actually change the name of the card to be the 
contents of the field?

Thanks,
--Scott