Help me with my windshield!

I had a guy come to the body shop with a 56 Chevy sedan and been to 2 different body shops and both places broke his windshields trying to install them and never got them in all the way.
I took the new windshield rubber and broken windshield and got it installed with a lot of work. Let it sit for a couple of days took it back out and installed the new glass and went to gather no problem.
Yea a lot of work but practice on the old glass and break the new rubber in and only buy one windshield.