Order Bose Companion 2 speakers. If you buy it directly from Bose or a licensed dealer, you can get a warranty in case you ever have any issues with them.
Decide where to put the speakers. Some popular placements are on either side of the TV, on the sides of the room or in the back corners of the room. Make sure they're raised enough so furniture doesn't block the sound. Look at the back of the speakers for the letters L and R. Make sure the L speaker is on the left side of the room, and the R is on the right side.
Plug in the cords that came with the speakers to the back of the speakers and the back of the TV in the "Audio Output" jacks. It's possible that you'll need longer cords if you have a large room.
Turn on the TV and speakers to try them out.