An enemy is walking up and down the path ahead.  We will use these Claymore mines to take care of him.  First watch his patrol path.  He just walks up and down the path, right in the middle.  Grab one of the mines then walk onto his path.  Just select the mine in your inventory to arm it, it will drop onto the ground.  Now run away a bit and watch the fireworks.  After you are done blowing him to bits run up the path to the next Training Area sign.