Profile is a little-used portion of the Mibbit client. You can enter your date, sex, location, home page, and a picture URL. All fields other than the picture URL allow for you to enter any amount of text. The picture URL field needs a picture.
Where do other people see this info in the profile? They see this info when one person on Mibbit whoises another person on Mibbit. There is no other place this information is used.