Connectivity

Hello - I just want to stream non apple music from my imac via the internet to hear on my homepod - how do I achieve this please?

how does everything need to be set up for this please ?

I should add - the homepod is on one apple ID - my imac another - I hope this is irrelevant as its NOT apple music that I want to stream and i just want to use the H-Pod as a speaker - nothing complex - just a speaker - on one home wifi connection.

Also - I am not using or intent on using an iphone or ipad - i just want to use the imac -

hope someone knows the answer please

I simply cant get the App to see homepod - I am sure this is my fault - but it is a mystery to me

Ideally I could stream the music to the homepod and a 3rd party airplay speaker at the same time - is this possible too ?

Thanks to one and all