I think I can do this on my iphone, but the imac I cannot figure out or see a way to successfully save a radio station you make -- based on an artist -- on new Apple Radio. Can anyone help me on this? Thanks!

See How to create, personalize, and find your Apple Music radio stations

On a Mac:

1. Open iTunes.
2. Click on the Radio tab.
3. Click the Recently Played title below the Beats 1 banner.
4. Scroll through your list of radio stations.