How to transfer files from iTunes onto my iPhone 5?

So recently, I converted a video into an MP3 file and stored it onto iTunes. I had just downloaded iTunes, so I'm unsure if there are any processes I have to do in order to move the file, but everything I've tried has not worked. I've attempted to sync my device with iTunes, but it keeps saying that to do so would mean that all my songs from the device would get erased, which I'm not sure I want.

Any techies out there know how to do this? I just want to move a song from iTunes onto my iPhone 5 device. By the way, I'm NOT using an apple computer.

Hi, you can try iPhone Transfer software. It enables you to transfer various files like music/movie/Pictures/TV Shows/Podcast/iTunes U/eBooks/Camera Roll/Ringtone/SMS/Contacts/Voice memos/Camera shot files between iPhone and PC/iTunes.

I use Video Converter Factory Pro to convert the video/audio file formats or into my iPhone. It keeps the original picture and sound quality, which is the feature I most appreciate. You can have a try.