The first thing you want to do is mount the drives. This will display a list of the hard drives PHYSICALLY connected to the machine. It will allow you to see USB drives connect to machine as well as anything connected internally to the computer. After mounting the drives in the system you will need to select the affected hard disk and select scan. The time that this will take will depend solely on the size of the hard drive and how many errors the drive has. As a side note a drive slaved directly into the machine will have faster scan times because it will be on the actual bus.