How do I find my pictures in iCloud?
How did you upload photos to iCloud?
Are you using My Photo Stream? Shared albums? Or are you using iCloud Photo Library?
Are you using iPhoto or Aperture on your Mac, or have you upgraded to Yosemite or El Capitan and are using the new Photos.app?
iPhoto or Aperture on Mavericks can show you the Photo in My Photo Stream or in Shared albums.
To see iCloud Photo Library you need to launch the Photos.app or open the webpage https://www.icloud.com and open the Photos.app there.