My name is Fran, I'm a spanish coin collector that is using this website since some years ago.
I can see that some coins are missing (for example Austria 500 shilling EU membership from 1995) How can add a coin in the catalog? I'll take my own pictures for that of course.
Well, it is simple. Go to catalogue (any country), then scroll down to the bottom. There is a link for adding new coins. As the new window opens, please take your time to read guidelines for editing (you will see it immediately).
Make a good request, and it will be validated (or you will be asked for another modifications). You will also see your modification requests in a new menu that will be opened for you under catalogue tab.
When in doubt, feel free to ask here on the forum or ask somebody from admin team (link at the bottom of every Numista page), but they are usually pretty busy.