In Japanese, there are various ways of saying "you", "I" and other things. We generally use あなた, however, we use her/his name much more than あなた after we know the name of each person. あんた is very impolite way of "you" but sometimes it's OK if it's used between very close people even though it sounds impolite and I wouldn't use it. I'd really like to recommend you NOT to use it.
I hope this helps you.