I can't add downloaded songs on my computer to my iPhone 5s?

[berrymanaf]

I'm pretty sure this has been posted before but my situation has never been resolved...

I have music downloaded on my computer, that I downloaded from torrents or YouTube etc.... Not legit iTunes files or anything like that... So I created a folder full of 300+ songs and dragged it into my local files on Spotify, made a new playlist, and set it up for offline use. Went on my phone and opened Spotify and set it up for offline as well. Nothing happens. I tried restarting everything several times and nothing. What do I do?