One of your rookie train drivers got confused about where to leave his train's railcars at the end of shift, so he just dumped them at the far side of the depot and went home.
You'll have to pick up the slack and put them where they need to be: alongside the train on the top track, and with the railcars in the exact same order, of course.
Take control of the train engine and sort out this mess!
All right, here's an example of a way in which this puzzle can be solved:
First off, move the engine over to the left and couple it to the railcars. Then drag the railcars to the top section of the loop and leave them there. You need to uncouple from both railcars, so make sure you touch the blue railcar, not the red one.
Continuing from Hint 1, move the engine all the way around and couple it up with the railcars again.
Your engine should now be facing left, with the red railcar coupled to it and the blue railcar after that.
If you've ended up with something different at this stage, you might be better off restarting the puzzle.
Now your train has the correct order, but now it's facing the wrong direction. You can move the train around the loop as many times as you like, but you won't be able to fix that.
To change the direction, you'll have to make use of the junction control level in the bottom right.
Touching the junction control level changes the way the tracks are connected. Try it out for yourself.
Now then, combine this with the information from the previous hints and see if you can work out the rest.