As @qdeathstar noted, the easiest way is to set up playlists on Spotify with your songs. I spent some time last year setting up playlists of all of my (200+) cassette mixtapes from the '80's and '90's - I can think of only one or two songs that were not available on Spotify - and I have a lot of underground punk and new wave on those tapes. Really great to be able to access them without a bulky tape player in my office - and on the go! I'm not sure whether you need to have a Premium Spotify account to do this or not - but it's only $9.99 per month (or $12.99 including Hulu, the plan that I have).What is involved to convert my usb music to streaming.
My update is installing now.