PNT area is pretty restricted; here's the only two things that you CAN do:
1. To reply to an admin's message in one of your own PNT's, you simply reply as normal.
2. To request additional admin consideration of a PNT, use
Considerations of topic promotions from the "Proposed New Topics" forum
Let me know if this doesn't answer your question. You didn't mention {whose topic you're replying to} or {why you want to reply} in your original post, so I'm not sure if this helps.
Note 1: I stole this sig. from AdminJar. Thank you!Note 2: I stole the "{}" notation from RAZD. This will be my first and only notation for ripping that off. Thanks!