Photo Stream will only upload the photos that are in your Camera Roll when the device is connected to Wi-Fi and the Camera app is closed.
You can do a Shared Photo Stream, though ...
Shared Photo Streams
Shared Photo Streams is an easy way to share select photos with just the people you choose. Friends and family can subscribe to your shared photo streams to view them on all of their devices, leave comments, and get notified automatically when you add new photos.
Creating a shared photo stream is as easy as selecting the photos you'd like to share and providing email addresses of the people with whom you'd like to share. You can share from any device using iOS 6 or later; from a Mac in iPhoto 9.4 or Aperture 3.4 or later; from a Windows PC with Windows Vista or later and iCloud Control Panel 2.0 or later installed. Learn more about creating shared photo streams.