I have a samsung plasma 50" tv, how do I hook it up to this sound bar? I tried to hook it up using the rca jacks and it didn't work.

Yes, follow what Jeff said and you may have to go into settings to enable the Audio OUT.

here are a few more things to check:
-make sure you going from Audio OUT on TV to Audio IN on the speakers.
-make sure the speakers are ON and functioning (you can test with another device)
-or you can try another speaker with the TV to see if the speaker is the problem.

Near the Audio / Video inputs on your tv, you should see a "headphone" jack or it may be labeled "Audio Out"
some sound bars plug into these jacks using standard heaphone jack.
Other sound bars may need to be connected to the device your using on your tv. (DVD player, cable box, etc.)
Tv speakers can then be disabled in the "Audio" menu of your tv.