Welcome, FLGrandma, so far you've done exactly right!
The "personal' messages differ from the posts in the fact that they are, as stated, personal. What's said in a PM is strictly between you and the person you're messaging, while posts are open to the public (remember that guests, not just members, can read posts). For these reasons, we encourage you to keep personal information to a minimum , and kind of general, in open posts...for example, saying you live in such and such a state (Florida, right?) or large city is fine, but I'd avoid small town names, and never post a specific address or phone number.
The email notification you received is just that, a notification.......replying to it will not reach the person who sent you the PM. I'm glad you went to the forum to reply from there, so your communication did go to the person you intended it for.