title tracking

Lately I've seen several films where a title or subtitle, sometimes in a box, tracks with a face, perhaps to identify the person, or as a speech bubble. The title moves in synch with the subject and/or camera movement. Now, I confess I'm a real newbie to motion tracking, so if you can tell me how to do this, please lay it out step by step, or point me in the direction of directions, so to speak. Thanks!

Well, if I had to do it, I'd use one of three ways. Which one, would depend on the length and the contents of the scene.
1) If the scene is not too long (let's say 5–10 sec), I'd try it in FCPX directly. Put a basic text from the title menu on your footage (e.g., a person walking across the scene). Then add a couple of keyframes (for a start: 1 kf per sec) and adjust the position of the text layer manually. Since it's just 10 or 11 keyframes for a 10-sec-piece, that's quite fast and easy. It might even be that 2 or 3 keyframes suffice.
2) Since transformation keyframes in FCPX are still not completely controllable, I'd prefer the way of opening the scene file in Motion and do the manual keyframing there. Then, just export the clip in ProRes422 and drag it back into your FCPX event.
3) More complex movements might require motion tracking. Personally, I think that if the movement gets quite complicated no one might be able to read the co-moving text anymore. But that's a different topic. To achieve this, you need to go to Motion and have Motion's tracker analyze your footage, let's say, a specific point on the object. Once this is done, add the text layer and assign a behavior to follow the tracking path.

Have you tried to look up "Apple Motion motion tracking" on youtube? There are many tutorials there.
I am assuming that you have Apple Motion correct? But if you want to track faces with no tracking points I would suggest lookup Mocha.