www. in the beginning of domain name

My websites gets no www. in the beginning of my website I get http://abc.com

I need www. in the beginning.

How can I do that?

RewriteEngine On

RewriteCond %{HTTP_HOST} ^abc\.com$

RewriteRule (.*) http://www.abc.com/$1 [R=301,L]

I don’t have a htaccess file.

Do I need it and where should I get one from? I have one from joomla will that work?

just create .htaccess file

And upload it to the root folder of your domain. But mod_rewrite must be enabled in your apache settings.