The old Sonos Home Theatre Playbar has an Optical connection to connect it to the Optical-out port on a TV. 

Is the Sub and the Speakers all Sonos products too? If so, what are they exactly? The model/name is usually stated somewhere on the speaker, or maybe post a photo.

It’s sonos speakers too, model name is “ONE SL” 

WIll the optical input from soundbar to the tv be enough for me to pair the other speakers up with it? Or do i need a ethernet connection for them to pair up?

Are all your speakers connected to your Sonos account? Or did you get them from someone else? If so they need to be reset, see https://support.sonos.com/article/reset-your-sonos-product

Then you’d start by connecting the the Playbar to your TV and set it up through the Sonos app, see https://support.sonos.com/article/set-up-your-sonos-playbar. Either connect the Playbar to your wifi or via the ethernet port to your router - if you choose the latter keep wifi on on the Playbar. The Playbar needs it to ste up the dedicated 5Ghz connection to the Sub and the surrounds.

After that you can set up the Sub and two One SL (as surrounds). The Sonos app will guide you. Then ad the other One SL’s to your system, putting them in a separate “room” in the Sonos. You can group the rooms, see https://support.sonos.com/en-us/article/group-and-ungroup-rooms?language=en_US This will result in a slight delay to the sound when playing TV-sourced sound. Music should be in sync.

Two of the One SL speakers and a Sonos Sub  can be ‘bonded’ (linked) to the Playbar over wireless and they then act as the rear left/right surround speakers in a 5.1 TV/Home Theatre setup. The other two One SL speakers can be used either separately or as a stereo pair and they can all be grouped/ungrouped together using the Sonos App - Note the Sub can actually be used with the One SL stereo pair if you perhaps prefer that instead of using it with the `Playbar, that’s entirely up to you.

Maybe see these hopefully helpful links too.

• https://support.sonos.com/en-us/article/sonos-system-requirements
  https://support.sonos.com/en-us/article/sonos-app-requirements
• https://support.sonos.com/en-us/article/choose-between-a-wireless-and-wired-sonos-setup
• https://support.sonos.com/en-us/article/group-and-ungroup-rooms