Hi Hibiscusfan,
You collected seed too soon. When snapdragon seeds are ripe, little holes will open up at the top of the seed pod, and at that point you can harvest the seed. The seeds will be black(or at least very dark.)
Remy

Thanks remy, I was hoping that they might ripen if I left them lay but I,ll have to let them ripen on the plant.

I just collected my first snapdragon seeds . Look for a little monkey looking face on the pod, these are the holes that the small black round seeds will come out of. Just shake the pod and they will come out.

I must be stupid but I don't understand what it is you are calling the monkey face on the pod. I have tried to look at the completed bloom and pull it apart but haven't found anything that might look like a seed. I'll try looking again today.

Hi Pippi,
Don't pull apart the bloom, let it die naturally. THe pods will appear where the flower was. When the pods are ripe little holes open.
The link below has a good pic of a couple pods on a stem. Notice how the holes have developed giving the appearance of a face on the pod.
Remy

Here is a link that might be useful: Snapdragon Seed Pods