Assuming the monitor has speakers built it, there should be an input (generally on the underside) it is usually green. There should have been a cable included (double male) that would plug in to the monitor input and then to your tower input, which is generally also green, this has to be hooked up in order for you to have sound.
Hey! I just bough Samsung 23" 2333SW LCD monitor but i have no idea how to connect the speakers to it. Can you guys help getting sound on it? I connected to monitor to my video card (inside processor), but I HAVE NO SOUND! PLZ help
Thanks in advance!
An help would be appreciated!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic