E: Couldn't find package on #apt-get install update

warrior:/home/rajz# apt-get install

Reading package lists... Done
Building dependency tree      
Reading state information... Done
E: Couldn't find package

This is may work by doing

#apt-get install update

but if the above error repeats for this command too.. then.

System>Administration>Software  sources (need root password)

In third party software tab click add

deb http://http.us.debian.org/debian/ lenny main

In Debian software make sure download from  is 'Main Server'
close it. click Reload. (This is important)
Open a new terminal window (close the existing terminal if any)
run the apt command again. It will work !