In Razz, you use the lowest five cards in your hand to make a hand. For example, if your 7 card hand is 87-QJ25-A, then your qualifying razz hand would be 8752A.
If your hand pairs, you can still use one card of the pair in your hand. However, I am usually cautious about playing the hand further, since you have one fewer card to use in your hand to make the qualifying hand.
Good luck. I have uttered many a cuss word playing razz cash games.