This is a "ramp-up" task for people who start to develop on Marble.

This is a preparation exercise for the task "Make the position marker configurable by adding a settings page":

The Position Marker plugin should receive an about dialog which displays the copyright notice, the license and all the other data that is usually displayed in the other plugins in this place.

Have a look at

http://techbase.kde.org/Projects/Marble/OnlineServices

and at the existing Online Plugins. The Wikipedia plugin has got an about dialog  that you can use as a "template".

Don't forget to add your name to the about dialog in addition to the other authors!