Use anonymous ftp to any CTAN archive
(see sources of software) and retrieve
the file README.uploads in the root directory. It contains
instructions for uploading files and notifying the appropriate people
for that site.
If you cannot use ftp, mail your contribution to
ctan@urz.Uni-Heidelberg.de and it will be passed along. You will make
everyone's life easier if you choose a descriptive and unique name for
your submission, so it's probably a good idea to check that your style
file's name is not already in use by means of the
`site index'
command (finding files in the archives).