I feel like an idiot. I misplaced the flyers this thing came with, so I don't know if I've overlooked anything important in the directions. How do I use it? I know I have to plug it in and charge it, but how does charging the batteries work? Do I just screw in the battery and it will automatically start charging? Do I need to press the button or hold it down? I notice when I press the button, sometimes it'll be red and sometimes it'll be green, and if I hold it down it'll flash at me. What does that mean? What do the colors mean?