Not sure about the kata editor, but you can create your own kata once you get at least 25 honor (which you have); just hover over your score in the top right corner and you should also get a "New Kata" item.

If not, report it here.

To fork, usually you get to do that once you solved it, then you can fork a solution (including the one of the author), like here; otherwise, just add "/forks" to the basic kata url.

Hope this helps :)