where is my music stored on icloud, I can't find it

You cannot access your Apple Music library from www.icloud.com at this time.

However, you can access your Apple Music library at beta.music.apple.com.

As per this article https://support.apple.com/en-in/HT204930

Apple Music isn't a back up service. 

Read this article https://support.apple.com/en-in/HT204926