I installed Wordpress today. I notice when i go to the website, there's no www before the domain name. is this because the site hasn't been indexed by Google yet??
No, it's because Wordpress has Network capabilities now and as a default excludes the "www" so that blogs can be created as subdomains or as folders.
That's a good question. I never even thought about trying to put it back. Why do you want to put it back? It doesn't make any difference what people type in, it will still go to your homepage.
Login to your WP admin dashboard then go to Settings > General, then in General Settings edit the following WordPress address (URL): Site address (URL): Add www on those entry. Usually by default the entries are http://YourDomainName.com After saving it will logout and will redirect you to login page again. Hope this helps.