Here's a video on how to obtain ALL of the prologue achievements, and more! Links to the specific achievements, in order of when you'll obtain them, are in the video description. I didn't show battles as some are walked through by the AI, and most others are simply auto fought and won. The last one appears very difficult, but my game cut out, and I didn't complete the prologue.
As for this achievement:
1. Start the game, and follow the steps. Claim your first outpost and build in it.
2. You will then run into an enemy and be walked through the battle, obtaining the first achievement.