The Website URL is where your visitors will first arrive on before being redirected away to another website or page.

For example, if you need to redirect http://mywebsite.com to http://mywebsite.ca for Canadian visitors, then the website URL will be http://mywebsite.com

Use your domain name if you plan to redirect your entire website or use a particular page URL if you plan to redirect only that page or its all its sub pages.

For example if you need to redirect http://mywebsite.com/blog and/or all its sub pages, then the Website URL should be http://mywebsite.com/blog