OP,
ignore @carlsbad , he is just misinformed.
I use the exact type of system you are asking about in two setups, my main system and my man cave.
You will need:
1) A 4K TV with HDMI connections (with something called ARC or eARC).
2) A 5.1 (minimum) capable receiver (Denon/Yamaha/Marantz, etc).
3) A set of matched speakers and a subwoofer
4) An X-Box or Play station
Your soundbar is really for watching TV, not gaming. Of the stuff I listed what do you already have and what do you still need to get?