You go to smilevideo.jp, log in using your Nico Account info, and choose a video to upload. (click the big black button)
Then, you wait.............
Once it's done uploading, make a title (in the spot where is says タイトル) and a description in the box under where the title is. Then pick a category from the list (カテゴリ)
I get this message where I'm guessing it says to secure your account or something, or atleast that's what it says in the URL.
When I click that, it leads me to a bunch of options or something. One column on the left has just titles, words, etc. and the other column has a bunch of black buttons to click.