Where do dragonflies come from?

There are several Families of dragonflies. If you are looking for the commonly used general classification name for them, the Order name for dragonflies and damselflies is Odonata. The Suborder for dragonflies is Anisoptera. Odonata Central (http://www.odonatacentral.org) has lots of photos and classification information if you are looking for the Family name for a particular type of dragonfly.