You had better tell us the model and year of your car so that the correct
information can be sent to you. There are several different methods in use.

Whatever your car, I can almost guaranty that you won't get it out
without cracking it.  And since no job like ever goes perfect without a
little practice, and the penalty for getting it wrong is pretty high,
this is something I'd leave to the pros.  I'm not sure where you are,
but around my area, you can get these guys to come to your house, pull
the windshield out, then come back and put it in later.

In the days when windshields were held in by rubber gaskets it was practical
for schmoes like us to remove and reinstall them (although reinstalling them
was a lot harder than it sounded, even with good string.) Modern windshields
are held in by adhesive, and are a job best left to pros.

Mike