ok...but I'm wondering that you get the update-package because you will get it only with a installed DNAS. Anyway...you can also use the provided docs in the package, which you can download on shoutcast.com.
tar.gz is a compressed archive like a ZIP. You have to extract it before you will get the files. You should do this with the same system-user, which was used for the existing DNAS installation otherwise you have to set the correct file permissions for each file after the extraction. If you only enter the path to the archive into the command-line, then you will get nothing more than a error-message as response.
These are linux basics and as I pointed, if you got the update-package, then you have a DNAS installed and I guess you know how to handle it. That is the reason for my question: What's your plan or better where is your issue?
Maybe is it easier to tell us, which linux-distro you are using, which DNAS version you are running currently, why you are using root instead of the system-user, where the DNAS is installed etc.
If you never managed a DNAS installation, then you will find many totorials with google:
If you stuck on a point, then tell simply where. To expect everyone is not able to use linux, when he/she ask about doing an update of a existing installation - I guess this inappropriate.