Share photos with itunes

You do not. iTunes is not a photo management program. It does not share photos.

Actually, iTunes is necessary if you wish to share photos with appleTVs

It depends where you want to share them to. As diesel says iTunes does not store photos but it does manage sending them from your folders or applications to devices such as iPhone, iPad and Apple TV.

If you want to share between computers then you need to use your computer not itunes

For dveices such as iPhone, iPod or iPad just choose which photos to send over to your devices on the Photo Sync page

For Apple TV assuming you have set up home sharing. Then

File > Home Sharing > Choose Photos to Share with Apple TV

Sharing pics with AppleTV via Photos/iPhoto is no longer available in iTunes 12.2.1.16. I hope Apple keeps breaking iTunes to the point it works again.