Hi. The Sonos Amp is what you need. This will connect wirelessly to the Arc and by wires to the speakers. The ceiling speakers will be the 'rear surround speakers' for the system. 

Thanks John. Wanted to understand the connection...I have 4 banana plugs in the wall & 1 red & 1 black plug to connect to the amp. Wondering how to connect to the right & left of thesonos amp?

Apologies, i am a newbie at this!

How many ceiling speakers are there?

Two

I am not sure what you mean by "one red and one black plug¹. How do these relate to the banana plugs? Are those plugs on cables? 

Apologies for the late response, pls see attached images. The 4 banana plugs go into the wall outlet, the other end of these plugs end up in 1 red connection and 1 black connection. Please advise on how do the red and black connect to the back of the sonos amp.

Thanks,

You need to get new speaker cables like these:

https://www.amazon.com/dp/B0713ZJDFG/

And connect them from the wall to the left and right channel banana plug jacks on the Sonos Amp:

Ok cool...will check it out!

Thanks for all your help