how to install adobe flash player with .tar.gz
Which edition of Netrunner do you have installed, 14, 16, 17, or Rolling?
Where did you get the .tar.gz file from?
Flash Player comes preinstalled on Netrunner.
The tar.gz is just a simple zip like archive. So if you really want to use that to overwrite the preinstalled version that comes with Netrunner first remove the preinstalled version with a package manager.
Extract the tar.gz archive and copy the files to the same folders you find in the extracted archive (usually found under the root of your filesystem).
The .so file needs to be put in /usr/lib/adobe-flashplugin.
This will work on Netrunner Ubuntu Base but I am not sure if this will work on 32bit and 64bit versions of Rolling