When to use the particle 嘛 ("ma")?

Hi guys! I'm only 15 and a Newbie here so please bare with me ^.^

I know when you ask a question, you use the "ma" particle but are they interchangeable with a question mark or do you only use one or the other? I mean, you wouldn't use both at the end of the sentence, would you? I just wondered because I see some Chinese sentences which use question marks and some that use "ma". Is there a "correct" one to use or does it not matter too much?

Thanks ^.^