Hi sailor95,
Unfortunately, locked missions can be a problem on many levels. If you are having trouble seeing what is going on in night missions, I suggest that you first try adjusting your monitor brightness and contrast before taking the extreme action of altering the mission.
If you must alter the mission, first be sure that you never Upload the mission or distribute it in any other way. It must remain for your personal use only.
Having said that, The Missions Manual that you can download from here:
http://80.95.161.114/shipsim/forum/index.php/topic,2886.0.html (http://80.95.161.114/shipsim/forum/index.php/topic,2886.0.html)
explains how to unlock most missions.
You don’t appear to have a problem with English, but you can get good Norwegian advice in mission creation by sending a PM to Tore (TJK).
And, of course, you can always ask questions here.
Med hilsen,
Marty