sending photos to icloud

When the settings are as per these articles Set up and use iCloud Photos - Apple Support

Change preferences in Photos on Mac - Apple Support

System Photo Library overview for Photos on Mac - Apple Support

To upload a single photo or more photos , if new photo is on desktop screen of Mac just drag and drop in photo folder of photo application click on import , it will upload to iCloud.com as well in photo application of Mac .

Read the articles Use iCloud Photos to store photos in iCloud - Apple Support

Upload and download photos using iCloud.com - Apple Support

See the instructions in Set up and use iCloud Photos - Apple Support

Note that after iCloud Photos is turned on the photos will automatically sync.

Also be aware that iCloud Photos is a syncing service. Any photo you delete from a device where iCloud Photos is turned on will also be deleted from iCloud and from any other device connected to iCloud Photos. You can potentially reduce the storage space required on a device by turning on Optimize Storage.

Apple does not currently offer cloud-only storage for photos. If that is what you want or need, you may want to explore 3rd party options such as Google Photos or Dropbox.