I don't know how to explain it

Simply plug the USB cable into your computer and then drag your music into the devices music folder.

Look here:
How-To Videos | Eclipse Media Players

Usually it's a good idea to find answers for your devices on the device manufacturers website. Troubleshooting or knowledgebase are good places to start. Also you can often download a new manual that has been updated over the one that came with the device, or if you lost yours. Most places will also let you e-mail them with questions too, but it can be slow to get an answer.