"Used to" refers to an action which someone did on a regular basis in the past, but not any more. He used to smoke a lot, but later he quit smoking. (he doesn't smoke any more) I used to go swimming every week, but I don't have time for it any more. There is a difference between "I used to do" and "I am used to doing" something. I used to live in a city. (I lived in a city in the past, but not any more) I am used to living in a city. (I live in a city and I've got used to it, so I don't find it strange).

"used to" is used with the simple past (usually) to indicate a habit/routine you used to have, but no longer do. I used to smoke (and now I don't) and he used to play the guitar really well (but now no longer does). etc..