I've never found much at wikihow that impressed me but here's a page that will give you some hope and get you started: CRC Error Fix
For things you don't understand there, just let gogle find answers for you.
Main thing is, you've got to run that command window with administrator privilege. You do that differently in every different version of Windows. Again, just let google show you the way to run command prompt as administrator.
Because Windows' graphic interface might not let you run checkdisk, that linked page shows you how to use the command line utlity for the same task.
Where those instructions say to launch diskpart be careful to type only that which they describe. Diskpart is a very powerful utility. Before you exit it, you can type help to see a list of some commands just to get an idea of things it can do. Don't try any of them without googling a bunch.
You'll also need to learn to navigate to different drive letters and folders using the command prompt. google will help you there, too.
Just make sure you know which letter your WD external drive is using.