[Plugin: Redirection] mysite.com to www.mysite.com easily possible with this plugin?

I’d like to change my site from http://mysite.com to http://www.mysite.com and preserve its rank. I know how to make the change in WP, and I’ve been told how to preserve SEO by editing .htaccess. I thought perhaps I could edit .htaccess indirectly through WP by using this plugin. If I can, please could I get some help as I am new to all of this and I am not sure what to change in Redirection.

http://wordpress.org/extend/plugins/redirection/