The artist commentary fields are used to capture any additional information the artist may have posted, be it title, commentary, or tags.
Adding the artist's commentary
You can add or edit information in these fields by first viewing a post, and then clicking the Add artist commentary link in the sidebar. A dialog with four fields will appear. Original title and Original description should have the artist's original commentary, regardless of the language it's in.
When adding commentaries, please make sure it is both relevant and significant. It must add something new and interesting to the image. If you can't read Japanese then the best course of action is to tag the post with commentary_request so that someone can read the commentary and determine whether it is interesting enough to be added.
If the artist posted multiple distinct commentaries across multiple sources, then preface each commentary with "Source Name:" on its own line.
Tags go into the tag section at the end of the commentary field. The tag section starts with "Tags:" followed by each tag on its own line. As with commentaries, please make sure the tags actually contribute something interesting. If the tags only identify characters then they should not be added.
Translating the artist's commentary
Translations of the commentary can be placed in the Translated title and Translated description fields in the Add artist commentary dialog.
See help:dtext for help with formatting commentary. Note that DText does not work in commentary titles, only the description.
source: danbooru wiki