I can use my passport SSD 1TB for copy and paste but it cannot find in WD Backup. So, I cannot add a backup plan.
Did you do a Setup when you first used the drive? I think it is on a new drive. I suggest you open WD Drive Utilities from WD Discovery and read Restoring the WD Software and Disk Image in Erasing the Drive by clicking Help at bottom left of Utilities as a guide. I have never done this myself.