An example of how co dominance can occur
If a red homozygous flower, and a white homozygous flower produce offspring, they will have red and white spotted offspring.
Pictures of co dominance
They have white spots, and the rest is black. They share the phenotype.
White and pink flower
The white and pink share the phenotype because it is bothe white and pink.
Flower that is yellow and pink
This flower shows co dominance because half in pink and the other half is yellow. It isn't combined to one color, which would be incomplete dominance. Instead it shows both colors.