Android: The Simple Help tech blog walks through the process of adding music to your Android-based phone using a USB cable and some simple file copy action.
The guide covers how to connect the phone to your Windows or Mac system by enabling the USB connection, adding the music to the Music folder (creating if it doesn't exist), and then turning the USB storage off again. It's really quite easy, but the Simple Help guide walks through the process in detail—so even the less tech-savvy can have music on their Android phone.
Hit the links for the full walk-through for your operating system, or check out how TuneWiki puts lyrics, radio, and social features into mobile music for your Android phone.
How to copy music to your Android phone from Windows [Simple Help] How to copy music to your Android phone from your Mac [Simple Help]