The DNG Converter has nothing to do with Camera Raw.
Camera Raw is a Photoshop Plug-in, while the free Adobe DNG Converter is a stand-alone application that runs independently of Photoshop and serves only to turn digital raw files from your particular camera model into raw DNG files that can in turn be opened with any version of ACR higher than 2.4.
To update the Camera Raw plug-in (ACR, for Adobe Camerra Raw), you need to go to Photoshop's Help menu and select "Updates…" (or whatever it's called in Windows; I'm a Mac user myself), and the Adobe auto updater should install the latest version of ACR for you automatically. The current ACR version for CS6 is ACR 8.1, which supersedes 7.4.
If that should fail for any reason and you have to do it manually, you need to download the ACR plug-in and follow the exact directions given in the download page. However, the Adobe auto updater has been relatively successful lately and the automatic download to ACR 8.1 should go smoothly for you.
If you're getting a server error message, it means the server is down. Try again a little later.
It can take longer during weekends for the Adobe folks to realize the server is down and fix it.
Incidentally, the DNG Converter you downloaded needs to be extracted from the compressed file (.zip or .dmg) and installed, not just downloaded. Once installed, you actually need to launch the DNG Converter application and run it manually on each new batch of raw files from your camera you need converted into raw DNGs for opening later in ACR.
It does not function magically, spontaneously or automatically.
But again, what you want is to update ACR to 8.1, not the DNG Converter, the current version of which is also 8.1.
Thanks for your help, I will download 8.1 and see what happens. I did extract DNG and did manually run it but its a bit of a faff doing that everytime.
Thanks for that now downloaded 8.1 and its working
Thanks for that now downloaded 8.1 and its working.