how do i turn on my home share on my mac so it display pictures on my tv through my apple tv?

Use Home Sharing to share media from a computer to other devices - Apple Support

You can view photos from your computer on your Apple TV.

• On your Mac: Apple menu ﹥System Preferences﹥Sharing﹥Media Sharing﹥Share Photos with Apple TV.

Key points about that Apple support page:

Once Homesharing is enabled on the Mac you can use the Computers app on the Apple TV to play videos and music from the Mac or view photos. The ATV needs to be logged into the same iCloud account as the Mac for this to work

Home sharing is used to access content that is downloaded into a computers iTunes (or TV app) library using other devices over the local network, it has nothing to do with iCloud.

People can use the same ID when setting both up but that doesn’t change the fact that they are separate things.

Yes - I overlooked that. The Homesharing method allows multiple people to access the iTunes content without compromising security of the iCloud account. However I suspect many people use the same details.

The ATV settings have different logons for iCloud and Homesharing.

It would be signed into an ID for home sharing, which is separate from iCloud.

If you are running the latest Mac OS then you would go into system preferences - sharing - media sharing and turn on home sharing

If you have a previous version then it would be done using iTunes (file - home sharing).

Your Mac would need to remain on order for the pictures to be accessible via Apple TV.