Since the changes to flickr there's lots of confusion on image permission.
Here's a bit of a primer with screenshots.
1. Click Edit at the top

2. Should see the following page below. Click Edit link

3. Select the one you want.

Now I do admit, I have not been truthful. I have many more images than the 300 advertised. And I wonder who/what is Dreadnought, Shining Hulk and Trunk?
You'll have to attend my meetups or expos to find out
