How to take night pics?

Is there an infra red flash for a nikon d3200?

No infrared flash. Even if there was, the camera has an IR filter.

The most straight forward way to take night pix is to get a fast lens, such as the AF-S 50mm f/1.8.
http://www.nikonusa.com/...F1.8G.html

Camera on a tripod. It's best to take night shots just after sunset. You get the city lights, but the sky still has colors of red to dark blue instead of the ink-black void that you'd get well after sunset.
For ideas and actual exposure settings, go to 500px.com and do a search for night.

Raise flash then fire!

How do you focus in total darkness? Turn the focus assist lamp on.

You don't have the manual? Use a flashlight to shine your subject.