What appear to be responses on a discussion thread are actually responses posted to your ad on the ad itself. They are just fed to that thread so that they have higher visibility. if you go to the original add and scroll down you'll see the comments and should be able to reply to them.
1964 Overlander | '08 Touareg V6
Current Project: 1964 Globetrotter
Parts needed: Vinyl folding door hangers circa mid-sixties