If you are new to WordPress you might be having issues to automatically add www to your WordPress URL. Well, don’t stress out, you just made a little error while installing WordPress on your domain. Follow these simple directions:
1) Login to your WordPress dashboard and navigate to the Settings > General mode.
2) In WordPress Address (URL) option, add ‘www’ before your web address, just like in the image below. But, make sure there’s no “/” in the end of your URL.
Now, if someone simply types “yourwebsite.com” into their browser they should be seamlessly forwarded on to www.yourwebsite.com. And this thing will not affect your Google rankings.