How do I put a song in my iPhone?

pu1. If you download iTunes and run it, there's synchronization
You can use that

2017-10-19

OK

pu2. You can't just do it. You have to use iTunes

2017-10-19

OK

pu3. It's a way to synchronize it with iTunes.
If you put the music in a specific folder on the PC, you can think of it as a way to synchronize the iPhone and the file and let it go in
I don't know what you're talking about, but you'll know when you download iTunes

2017-10-19

OK