Debian: install flash plugin(the "non free flash plugin")

Please verify if the following command has no results:
apt-cache search flashplugin
if has no results
add edit, as root, /etc/apt/sources.list file
and add a row as follow.
Take the row with the current version of your debian
(in my case "squeeze")(not squeeze-updates....or others......)
and "main" as branch version.......

In my case I take the 2 following rows 
deb http://ftp.it.debian.org/debian/ squeeze contrib
deb-src http://ftp.it.debian.org/debian/ squeeze contrib

After this I give
apt-get update
to reload all available packages
and again
apt-cache search flashplugin
to search.... I have this results....:
flashplugin-nonfree-extrasound - Adobe Flash Player platform support library for Esound and OSS
flashplugin-nonfree - Adobe Flash Player - browser plugin

So I give
apt-get install flashplugin-nonfree
restart firefox browser
and all is done....

Bye.....