No problem!
First, if you haven’t already done so, install missing-e
Once you’ve done that, go to missing e settings on your dashboard:

Then click “Social Features,” scroll down to “Reply Replies” and click the switch to turn it on. From there you can customize the avatar size and whether or not you want their username to be tagged in the post.
To actually reply to a reply, go to the notes of your post. Next to a user’s reply is the arrow icon. (it works with photo replies, too)

Click that, and it will open up a text post of the reply in a new tab!

And if this is your first time using missing e, don’t worry, it’s not going to corrupt your computer. Explore the other options because there are so many other ways you can customize and enhance your dashboard and posting features! :D