This may mainly depend on the make of the 3D TV or rather screen that you may be using for there are actually different 3D formats that also work quite differently.
Being that some have 2 images for everything,
one for left and one for right It`s usually plug and play.
and still it depends upon the TV .It also depends on the DVD or blue ray disc,
Some of the discs have regular as well as 3D versions of the same disc.
You also need proper 3D glasses,
if you are using any other kinds of glasses it may result to no actual benefit.