This achievement takes place in the 1st level of the game and is really simple to miss if your not paying attention. Shortly after exiting the first room you should see a stair case on your left. head down the stair case and you should find the terminal. When you hit the terminal by pressing X the achievement will unlock. The terminal pretty much gives you a background about what Master Chief has been doing throughout the series of the Halo games. So its good to listen to the whole service record to get a nice recap, especially if your new to the Halo series.