Assuming you are talking about a standard DSLR camera battery, there are a few different ways to charge it. The most common is probably using the charger that came with your camera. Just plug it into the wall and attach the charger to your battery. Some newer cameras come with USB charging capabilities, so you can just plug it into your computer or any USB port to charge it up. And finally, if you are in a pinch, you can always use AA batteries in your camera as a backup (although this is not recommended as they will not last as long as your normal camera battery).