How do I share posts in the "Show" section?
I tried to use "Show HN:" but it's not showing up there.
Show HN is for showing your own work, something you've built. That's not the case here, as you are marketing an existing company that has employees (of which you seem to be one). HN readers have an aversion to blatant advertising so I wouldn't recommend that strategy here. Finally, your submission title implies that you made this product, which I think is misleading.