OLD computer won't back up!

I am trying to back up my 12 yr. old desktop before I wipe out the hard drive and give it away.  I have a WD My Book 500 GB external drive.  I go into the “Backup” tab, but I don’t have the icon to click “Start Backup”.  I only have “Pause Backup” (which I can click on) or “Run Backup”(which I cannot click on).  Can someone help me please?  I’m not terribly techie, but can usually figure stuff out.  Except this one.

Hi Download the latest version and try it again.