You won't need a map for this particular mission objective, because all the fights will take place near the landing zone. You can stay on the asphalt road for a few more seconds in order to take out an enemy truck. Otherwise proceed directly to the top of the hill. There's a small dirt road leading to it (screen).
Park your armored truck somewhere near an allied plane, but don't exit the vehicle. Instead, use your main cannon to take out enemy troops. You'll probably have to kill 5-10 soldiers. Thankfully, none of them is using a rocket launcher, so it's going to be a piece of cake.
As you've probably noticed, securing the top of the hill hasn't solved the problem. Go back to the asphalt road using the same path you've chosen before. Notice that a new group of enemy units has arrived in this area (screen). If you don't want to damage your vehicle, consider leaving it and fighting them on your own. You could also remain on top of the hill to use a sniper rifle. Either way, you'll have to wait for a new assignment to be added to your list of primary goals.