I think that I can describe the installation of f-prot on Knoppix 6.4.4, but I don't recommend the use of any Linux system if your HDD has an NTFS filesystem.
I suppose that you have downloaded the file fp-Linux-i686-ws.tar.gz and saved it to the home directory /home/knoppix. If that is the case I would open a terminal and issue the following commands
The install program asks some questions which could be answered by hitting the enter key. You must have a working internet connection because the virus definitions are quite old and really need an update.
sudo tar xzvf fp-Linux-i686-ws.tar.gz -C /opt
After installation, the virus scan program fpscan can be run in the command line (terminal). I think that you have to be root in order to do a full scan of your system.
Don't hesitate to consult the documentation of fpscan if you are unsure how to use the program. The manpage can be read in the terminal by issuing