How do I "upload"to my MP3, from my PC..?

Answer 1

Plug it in and open Windows media player. Click the Sync tab. You should see your player there and just drag and drop the songs you want to upload.

Answer 2

It depends on what mp3 player you have. If you have an iPod or a Sony, you'll need to use their specialised software to synch up the device to the computer and transfer files. If you have something like an Archos or a flash stick, you can just drag and drop the files in, like you would with a portable hard drive.