Force www.MyDomain.com or without www (MyDomain.com) in a URL

I would like to force my sites to show www.MyDomain.com
or to show without www. How can I do this? This is easily done with our
linux servers by using the following .htaccess directives. .htaccess is
a regular text file that can be created in the file manager located in
your control panel or by uploading a text file. .htaccess tells the web
server to use the directives that is in it. Force www:

#Force WWW in address bar
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

Force Without WWW

#Force Without WWW
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.(.+)$
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]