It depends if it’s in a question or not.

Ça va ?

Ça va bien ?

Comment ça va ?

They mean the same thing. They can all be used in casual conversations, but if you’re talking to your boss or something "comment ça va ?" is a little better ("Comment allez vous ?" if you have to be very formal).

When you’re answering, you can say "Ça va.", but not the others.

Anyway I answered this one but I suggest you read other answers before asking your question. You’ll most likely learn much more with other questions, especially if you’re just beginning. Chances are the question you want to ask has already been asked (and answered) by other people !

Two things:

• Don’t forget the cedilla on ça. Without it, it’s not the same pronunciation and it doesn’t mean anything (it’s tolerated to omit it on a capital letter despite there is still a debate about it).

• You didn’t use question marks. It’s important because in spoken/informal/everyday French it can be the only difference between a question and an assertion (as it is in English I suppose?):

Tu as faim ? = Are you hungry?

Tu as faim. = You are hungry.

That being said…

Side note: don’t forget there is a difference between using vous (vouvoiement) and tu (tutoiement): http://www.french-linguistics.co.uk/grammar/tu_and_vous.shtml. Using tu can be considered rude with some people, as using vous can be excessively polite with some people. So in the following, I won’t consider this aspect of the language, but only the grammatical form of the question.

QUESTIONS

• Formal:

Comment allez-vous ? (vouvoiement)

Comment vas-tu ? (tutoiement)

• Less formal:

Vous allez bien ? (vouvoiement)

Tu vas bien ? (tutoiement)

Comment ça va ?

• Informal, everyday language:

Ça va ?

Ça va bien ?

ANSWERS

The answer ça va (or ça va bien) can be used with any question type (open (WH questions) or closed (yes-no questions)) and any language register. If you want to be really polite, use je vais bien instead of ça va.

Of course you can answer closed questions with oui or non.