, just the beginning part.
Another way of putting it is say that I'm recording a game and as I am moving, text appears and it stays where it is and I walk through the text.
Sorry if you can't understand that well, I struggled trying to explain it.
You need to motion track your footage. make a null and target it with the tracking data, then parent your text layer to the null and do your positioning. you can find a number of tutorials if you just search for motion tracking.