how do i get music in my itunes library to download to my phone so i can download it to my watch?

i have not yet succombed to a subscription with apple music. Over the years, when we used to import our cds to our computer, I have built up a library of imported and purchased on itunes music. I have downloaded some of my music library to my phone, but now when I open the music on my phone, for those that are not already downloaded, i'm not seeing an option to do so. I don't see an option to download on the pc in itunes either. I see all this music but I can't get it my phone and then to my new apple watch. The whole idea is to download a bunch of favorites and not have to bring the phone to walk the dogs, etc.