See Profiles for a list of all author pages.
Short version of intructions: To use your profile just edit any page, click on author link in All Recent Changes and edit away.
Pending instructions: Redirecting old pages; Listing pages that link to your profile
This list was used to maintain all the various personal pages from the old wiki. There were rather a lot of them and locating them could be a problem. See above for instuctions on maintaining a Profiles page instead.