Head towards the village. Before you approach it, try to perform a good reconnaissance (you can use the help of D-Dog and Quiet), because it is a good idea to avoid being spotted, throughout this mission. Head towards the main buildings. It is best to walk around the child soldiers that you encounter, or walk around them. In the case of the former, remember that the children need to survive, so use sleeping ammo weapons (if necessary, you can also rely on melee, but then you risk that you alarm others).
The first one of the characters that you need to extract is the captive XO. He is being held in the shelter in the central part of the village and he has been shown in the above screenshot. It should be noted that, around the POW, there also are several children and you will have to keep this in mind, because you will soon try to rescue the prisoner.
The other target to find is the child soldiers' commander. He is not staying in one specific point of the map, but you can usually find him near the abovementioned XO. You can tell the commander by the red beret and usually, he is accompanied by, at least, one guard.