Originally posted by Tom:

This thread is very old but unanswered, i hope my comment doesn't count as necroposting.

Anyways, if you don't know how to submit in the workshop yet, you have to:

1) Create something in the editor.
2) Click on "save".
3) Click on "new file".
4) Write a name for it.
5) Save it.
6) Click on "share".
7) Optional: Lock it so nobody copies your skin (or not).
8) Optional: Filter if it has mature content (or not).
9) Upload it.