In Settings>>General I am missing some fields

I am new to WordPress and downloaded the 3.5.1 version from my hosting provider. I want to add www in front of my domain and I read from many sources how to do this. Go to settings then general and change it there. Thats fine except my screen in General looks nothing like the instructions I have been following

It does not have a place to change the Site or WordPress URL. Am I missing something
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Solutions Collecting From Web of "In Settings>>General I am missing some fields"

You are in the wrong settings page. Your site is a multi-site setup; the URL is set in the site manager, not in individual sites.

Go to Network Admin/Sites in the My Sites menu:

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Select a site to edit:

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Change the URL:

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Update

You need a subdomain setup to get editable URLs.

See Create A Network for the installation guide and Configuring Wildcard Subdomains for the server setup.

It looks like your hosting provider auto-installs a modified version of WordPress.

You should consult them, or remove this install entirely, and do a manual install in its place.

EDIT: I defer to Toscho.

it looks like you are using a wordpress website hosted on wordpress.com. The tutorials your are following are for the wordpress you download and install it yourself.