There's no programming in the MED itself, but you can create WAC files to go along with a mission (they do extra stuff you can't do in the mission editor).
They have their own language. It's If (Trigger) then (Action) Endif, basically (Endif is kind of like End If in .NET. I think that's where they copied it from.
What programming language(s) do you know? I'm trying to learn Java.