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hello I don't know how to upload a steam workshop level.  how do I because I got the game on itch.io. So can I know how to do that?

(+1)

Since that relies on Steam workshop it is not available in the itch version.

If you download the Steam version, all your data is shared, and you can upload it from there: 
https://itch.io/t/67604/how-to-get-a-steam-key-from-your-itchio-purchase