You just need to install the programs you're trying to run,
you can get them in synaptic, or just copy-paste
If you're ever in doubt, search through synaptic, or from a command line "apt-cache search psutils" (or whatever other program you need)
sudo apt-get install psutils sane-utils
On a side note:
ln -s /etc/init.d/cups /etc/init.d/lpd
Probably require root permission, i.e. sudo, i.e.
sudo ln -s /etc/init.d/cups /etc/init.d/lpd
sudo mkdir /var/spool/lpd
If the "mkdir" commands tell you the file exists, than no worries. This command just makes a folder, so if the folder already exists, no problem. And just so you know, the "ln -s" command makes a symbolic link, which is like a shortcut (it basically allows you to give files different names, and link to them from other directories for convenience)
When they say things like "superuser authorization is required, blah blah blah" they mean that you need root (administrator) permission, and the way to run a command as root is to prepend "sudo"
Most things outside of your home directory (/home/username) are owned by root or some other user, so if you want to modify them, you'll need root permission.
If you're ever curious about a command, try "man commandname" from the command line to get more info about it (q to quit back to prompt)
I would strongly suggest a basic command line tutorial as well, it's not generally necesary, but often a great way to get things done and investigate problems, you might want to start here in the ubuntu documentation tutorial on terminal handling.