how do i save the shared photos on my apple tv to use them as my screensaver

Welcome to the Apple Community.

Any photos you share from your computer via the advanced menu in iTunes, will also available to use in the screensaver settings on the Apple TV. There isn't anything special you need to do.

I struggled with this as well. You have to:

1. create a folder specifically for you Apple TV screen saver...title doesn't matter.
2. go to menu on you apple tv screen saver
3. choose foler that includes pic you want
4. open folder
5. highlight pics
6. they will download to you screensaver library, like on your MAC

The one thing I do not like is that the speed is too fast and no settings to slow it and that the only two potimal choices are collages. I would like a single pic to show at one time.

Hope this helps.