You need to make sure you don't pick a drive that is already in use as all contents of it will be overwritten during the process.
Click on 'select a disk to clone to' on the next screen, and pick the new drive.This copies all contents of that drive to the destination drive. You find the 'clone this disk' option below the drive once it has been selected.The main hard drive with Windows is listed with a small Windows-icon in front of its name and drive letter. Select the hard drive that you want to clone.If that is not the case for you, make sure the Disk Image tab is activated. Macrium Reflect Free displays all drives in its interface on start.Install and run Macrium Reflect afterwards.