There is not night mode. You're beyond that now. The only difference between day and night is the amount of light so you need to learn to adjust accordingly. There's a thread with general tips and suggestions in this forum that will help you a lot.

You have a dial on top of the camera with numerous modes. Look for S/M/A/P on the dial, they're important. S = Shutter, M = Manual, A = aperture, P = Program.