Hi Leaive,
Mvsmith wrote some very helpful notes for the use of the mission editor which can be found here (http://80.95.161.114/shipsim/forum/index.php/topic,19793.0.html).
Besides that, Wouter from VSTEP made some very clear video's which can be found here (http://80.95.161.114/shipsim/forum/index.php/topic,23370.0.html)
You can ofcourse also find it in the manual that comes with the installation of ShipSim