If I am understanding your question correctly you want to know what to fill in for Auth token (oauth_token), Track Title (track[title]), The file (track[asset_data]) correct?
oauth_token is a private token you get from soundcloud. You will have to sign up for there developer program to obtain one of these:
http://www.developers.soundcloud.com
once you have one you will replace
this.Token
with they key you obtain.
the track title is simply the title you want to name your track. in
form.Add("track[title]", "Some title");
simply replace "Some title" with your own title.
for asset data, you want to change "Downloads//0.mp3" to the path of the file you want to upload.