The Tenor clef looks like this:
The clef points to the letter C, which is why it is also called the C clef. That C is middle C, (2nd finger on the A string for cellos, or 3rd position on the G string for Basses)
One way to think about Tenor clef is that the notes are one string (a perfect 5th) over from where they would be in Bass clef. Here is where middle C is located in each clef: Treble, Bass, Alto, and Tenor.
Here are two video examples to help explain and demonstrate.