Any photos of ringed wild birds (alive or dead) in which you can read the ring number can be posted on the forum and I will try to recognise the individual involved. Remember that it is best if the whole number is visible, especially the last three digits.
Alternatively, as Mike mentioned, contact the society.
If you are lucky anough to find a bird ringed overseas, please remember to contact the HKBWS or Bird Ringing Group as well as the overseas authority responsible for ringing the bird.