'hg commit' : abort: no username supplied (see "hg help config")

[Alan Mackenzie]

Hi, XEmacs.

When I do "hg commit", I get the error message

    abort: no username supplied (see "hg help config")

.  hg help config gives a list of possible config files, and when I get
as far as 'man hgrc', my eyes start glazing over.

Would somebody please give me a quick tip on how to fix this error, and
possibly even warn me of other things to come.

Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).