Commentaries on Avinu Malkainu?

I need a little help that I’m sure I can get from the chosheve olam here. I told my Partner in Torah that we would learn some things from the Rosh Hashana davening this year. Since she said that Avinu Malkainu is something that it said in her Reformed services, I would to learn it with her.

Can anyone tell me some interesting explanaitions or vertlach? I am surprised to find that this information is harder to find than I thought.

Thanks.