This article explains how to transfer music from a computer to an iPhone. Instructions apply to the iTunes app for PC and Mac. You can also transfer music from one iPhone to another.
How to Transfer Music from Your Computer to Your iPhone
There are a few things to consider before transferring music to an iPhone. Follow this checklist before proceeding:
Follow these steps to connect your iPhone to your computer and select it in iTunes.
Connect the iPhone to the computer with a USB cable.