"How are you, boys?"
"Ça va bien les garçons ?" seems correct to me. Is it wrong because it's missing a comma?
I think "Ça va bien" is more "Are you well" as opposed to just "How are you".
French grammar requires articles more often than English. Just like how "Je mange du pain" literally translates to "I eat of the bread", but in English you would say "I am eating bread."