Redirect from no www to www

Hi,

I would just like to know exactly how I would redirect from:

http://ruarkmosaicart.com/contact-2/

to

http://www.ruarkmosaicart.co.za/contact-2/

Does the www matter?
Below is a link to a screenshot that I have made showing what I have done. Is this correct?
Screenshot

Thank you.

https://wordpress.org/plugins/simple-301-redirects/