For this setup, the usual solution is to combine flash with a longer exposure. The flash lights and freezes the person in the foreground, while the longer shutter captures the city lights in the background.

A tripod or other solid support is strongly recommended. It reduces camera shake, lets you use lower ISO for cleaner images, and makes long exposures much easier. If you don’t have a tripod, try resting the camera on a wall, bench, or bean bag—but your framing options will be limited.

A great trick for city night shots is to shoot at twilight/blue hour instead of full darkness: the sky still has some brightness, while city lights are already on, making exposure easier and often more attractive.

Handheld long-exposure shots are possible, but the background will usually blur. That can sometimes be used creatively for a dynamic effect.

For moonlit landscapes, support is even more important because exposure times are typically long. In general, steady support and careful timing matter more than expensive gear for this kind of photography.