I frequently like to take pictures with friends at night. The trouble with that is when I use flash to illuminate the people, the background becomes dark because of the fast shutter speed. If I lower the shutter speed, then the exposure will be much better but the people I'm taking will become blur because they move even though I'm using a tripod.
So I heard about this solution where you take a picture of the background properly exposed, and another with the people properly exposed and somehow merge the 2 pictures together using layers. But what do we do exactly? Is there a step by step guide? Also, do I take the picture of the background without anybody first or do I ask my friends to be in the picture?