This is a very simple task. You will only have to reach a nearby landing zone in order to pick up new charges from an allied gunship. Start moving towards your destination. I would recommend that you choose a small path that's located on your right (#1). Thanks to that, you shouldn't come across any units. Head on to the gunship (#2). Press the X button in order to take the C4. You can also arm yourself with new weapons. CHECKPOINT 5.