No worries Geoff. On the showcase threads people normally reply to the general thread (that’s by using the big square reply button right at the bottom). If it’s a more chatty thread, and you want to reply directly to a person, then use the grey “Reply” directly below their post. There are lots of threads on various themes where you can showcase items of your own. Then there are threads like this where you showcase items from other shops (and they do the same for you). To get seen more widely, outside of the Folksy Forum, can be challenging and I’m no expert but if you visit the Folksy blog, there are lots of articles with all sorts of advice (to find the blog, go to the Folksy front page and scroll all the way down to the bottom and click the “Blog” link).
Hope this helps and I wish you the best of luck with your shop.