If you look at the triggers in that map you should see something along the lines of:
Turn LEFT
Event: when Left is pressed
Action: Set Left=true
Stop LEFT
Event: when Left is released
Action: Set Left=false
Actual Movement
Event: Every .1 seconds
Condition: If Left=True and Right=False
Action: if(forward=false) Make UNIT face (Current rotation +5)
else Move Unit (Current rotation, 100 distance)
There you go a simple way to turn a unit. Do the same thing for right. Do the same for moving forward and backward, making sure to check that left and right are not being pressed. It's really rather simple you just have to think it as a step by step process.
AND if I may say, this doesn't belong in the request section, put it in the trigger section.