A Comment is a small amount of text you can show to other users. There are currently two types of comments that can be displayed in different situations; Bazaar Comments and Search Comments.
A bazaar comment appears when a user examines you using the Check command. Your text appears just below your equipment. You can edit this text from the Main Menu (2nd Page) > Bazaar > Edit Comment.
A search comment appears when a user selects your name from a search menu. The text appears in green in the chat log. You can edit this text from the Main Menu (1st Page) > Search > Edit Comment.