It sounds like you’ve got an exciting project on your hands! The OBD port on a 1993 Ford Ranger is located under the hood on the left side of the engine compartment. More specifically, you’ll find the OBD port in the same place as the fuse and relay box.
Since your Ranger was manufactured before 1996, you’ll be looking at OBD-I codes rather than OBD-II codes—as is standard in all American vehicles built after 1996. While you’ll likely need to use online resources or a trouble code book to unpack your Ranger’s trouble codes, here are some common codes that might appear for a 1993 Ford model: