For this achievement you need to enable the tutorial. You have to play on rookie - commander difficulty to be able to play the tutorial.
Once the tutorial mission starts there is not much to do. Everything is scripted and you just have to follow the mission markers. As soon as you have finished the mission the achievement will unlock.
One word of warning though: As mentioned in the comments, enabling the tutorial will void the "the untouchables" achievement (complete a game without loosing a soldier) as there are two soldiers inevitably dying in the tutorial.
(video credit: Spawnster)
Hope this helps you guys!
Any improvements? Please let me know in the comments below!