Basically to add a printer you need a to have the drivers and something that
links the computer up with the driver and controls the printing process.
CUPS is the intermediary. It stands for common Unix printing system and it
was developed by Apple for OS/X which is a Unix derivative, like Linux.
CUPS is a print server, spooler and scheduler all in one.

CUPS is installed by default with most distros. You still have to install
the printer so that you can use CUPS. Each desktop environment has a
different method of installing a printer. In KDE it is done in the System
Settings control panel and in GNOME it is done from System, Administration,
Printing.

Also useful is Foomatic. It is a filter that works with CUPS and handles PPD
(drivers) files and works with other utilities such as HPIJS from HP. Since
it handles drivers, you need to have Foomatic installed. Also useful is
Gutenprint. It includes most, but not all drivers. You will also find some
extra drivers for some printers in the miscellaneous text sections of
Synaptic. Don't go there until you have exhausted other possibilities.
Note: Not all printers are supported. There are some that will never work in
Linux and some that only partially functional. Fortunately printers are
cheap and you can often buy them on sale for little more than the cost of
new cartridges. (Which makes the environmentalist in me cringe.)

So:

Open Synaptic (System, Administration) and Search (not quick search) for
CUPS, Foomatic and Gutenprint. Make sure all are installed. If not, install
them. In addition, if your printer is HP then you can install HPLIP.

To install a printer, Go to System, Administration, Printing and choose New
Printer.This gives a visual guide:
www.freesoftwaremagazine.com/.../printing_ubuntu

This is your printing bible: https://help.ubuntu.com/community/Printers

Sorry, but I am in KDE so I can't step you through it. (I have given up
GNOME in my own little protest until they remove Mono.) :)