How can I use a window for an emergency exit?
I personally would doubt the veracity of the quoted report, since they say


  I have no recollection after I got out of the plane


I would wager that their recollection of the moments just prior could be faulty.

Nevertheless, to try address your question, my answer is: you don't need to, and you better not try, you would be wasting time.

Aircraft are designed such that complete evacuation must be completed within 90 seconds using only half of the available doors. Trying to open a breach through a window would take much longer than that, would cause otherwise avoidable injuries, and in general would create an opening that is generally quite small for a person to go through.

Your time and efforts are much better spent in reaching a normal emergency exit.

The only situation where exiting through other passages could have sense, is when the impact has created breaches (large enough to pass through) in the hull for you, but the likelihood of you being conscious then is quite low.