Why doesnt my site appear when i type the www in front?

Probably because the site does not have it's "Host name" site bindings configured correctly in Internet Information Services (IIS) to except the (www. version) requests to "www.yourdomain.com".

If you have access to IIS here's how you can add a host name for "www." + yourwebsitename.com":
1. Open Internet Information Services (IIS) Manager. Note: this example uses IIS7
2. In the Connections pane, toggle open "Sites", and then right-click on your site.
3. In the dialog box, click "Edit Bindings"
4. In the Site Bindings pop-up box, click Add -> then in the "Host name" text box type: www.yourwebsite.com -> then click OK -> then click Close.

After making those changes, your website should now resolve to the "www" version.