Plug the USB cable in an available USB connetor of the computer.
If it's a eSATA kind, you need to plug it into an eSATA connector.
You may have to also connect it to a power outlet depending on the model.
In Windows (any version), open the explorer. It will show up as Removable drive, possibly named as the brand or model of the catual drive. You will need to wait a little to allow windows to actualy recognize the drive and get ready to use it.
If you have a Mac, you need to mount it. Same thing if you are using Linux, any distro.
Once it's done, you can access it in exactly the same way as your regular drive.
Electro, December 2011