XF 1.3 Avatar/Post Customization (Answered)

Two things: 1. Hopefully this isn't too small of a question and 2. I can't think of a better title for this.

I was browsing a XenForo forum and noticed that under the Avatar of a poster was this:

I know you can add custom fields to profiles, but how can you add them under a user's profile under a post like this? Thanks.

Edit: For clarification, I'm pointing out the Terraria: field.