Hi @peterears

If you want to reply to someone's post you can hit the "Reply" button beneath their post and then a box will appear where you can reply.

You can also copy their name and put it first on the post (like I did when I started this post with @peterears). These are two ways that the person you want to respond to will get a notification that you posted to them. I usually do both.

I hope that helps!