The OBD-II port may be located under the dashboard, towards the driver’s side. It is usually near the steering column, and maybe covered by a plastic cover.
2003-2009 Models
The OBD port is located under the dashboard, on the passenger side. It may be covered by a small black cover.
2010 Models
The OBD port is located in the engine bay, near the passenger-side front wheel well. It is usually in a black plastic housing.
For all models:
If you still can't find it, consult your vehicle's owner manual for the exact location of the OBD port.