Roland VS-1680 i need help

I bought this digital studio workstation off a friend, so i can get started on some recording for my new album. It works great, the only problem i have is that i dont know how to export, or import files. I want to get some drum tracks on the but i cant. Unless i use an electric kit, but those suck. I have a drum software and everything.But i just cant get the track on my workstation. I've tried RCA cables, and they dont work. It only works on the outs. I need a cable or usb that can send data into it. And also, how would i export my final recordings so i can master them on acid?...If anyone can help, it would be greatful.....Thanks