I have a solid wooden door with the three little diagonal windows that were so popular in the 50's. I have purchased pebbled glass, three pieces to replace these windows. The glass is long enough to be of an equal length both top to bottom. I have never installed a window from "scratch. How do I do this project? Please respond with simple directions. The pebbled glass was quite pricey and I can not afford to buy more if I break them. Thank you. Jo