I just ran a Google search for your devices and came across this FAQ page for Sony Walkman NWZ-E385:
http://www.sony.com.my/support/product/nwz-e385/faq
Reading through the information in there, it appears to me that if you want to transfer media from your computer to that device or vice-versa, the best way to go is to install the Media Go software in the computer and use it to do that job. Here is the link to download Media Go:
http://mediago.sony.com/enu/features
You need to install this software in the computer, plug in the Walkman using the connector cables that you have and then using this software, you need to transfer the music to the device.
Does that help?