Do I need to setup a 301 redirect for www and non-www versions of my website?

Hi

I am using the Iconic One theme in WordPress.

I was configuring Google Webmaster for my website (http://thewisdompearls.com) and I found that there is something called “Preferred Domain”.

Reading further on that it indicates to setup a 301 redirect for the non-preferred version so that it can redirect to the preferred version.

I currently have http://thewisdompearls.com in the WordPress Dashboard >> Settings >> General under “WordPress Address (URL)” and “Site Address (URL)”.

Under Google Webmaster settings, I see two versions on the dashboard home page. One is the http://www.thewisdompearlcom and the other one is simply thewisdompearls.com

In the Site Settings section of Google Webmaster I have selected the preferred domain as “thewisdompearls.com”

Now do I need to make any other setup in regards to the 301 redirect? I read something about .htaccess file?

This concern came up since I am seeing two different dashboards in Google Webmaster with different set of web data (impressions, clicks etc) for the www versus the non-www versions of my website.
Does it really matter?

Thanks
Samkit