i have a samsung slimfit TX-T3093WH and im trying to hook up some speakers to my tv. (i dont want to use the speakers that are built in to the tv)

do i just plug in the speakers to the av-out jacks and im done?
do you have to turn off the built in speakers? (if so, how?)

Generally you have to hook speakers to an amplifier. The A/V jacks get cabled into an audio amp or A/V receiver, and the speakers are plugged into the speaker outputs of that amp.

Once you have that working you DO turn off the TV's internal speakers. There will probably be an option to do that in the menu system.

Another option is to buy self-powered speakers, like those used for computers.

With wire.

Sorry, I couldn't resist :D