Google: fellatio deep throat
http://www.sexuality.org/l/sex/fellatio.html
Read Lesson Five and Eight.
It's possible. You need to establish a strong trust bond because you can seriously injure a girl's throat if you can't control yourself (e.g. thrusting movements can bruise the esophagus). Most women can't deep throat like Heather from ideepthroat and probably wouldn't want to try either.