First of all, turn your car on and put your heater on the defrost setting at the highest temperature with the fan on low. If your car has air conditioning, turn your a/c on as well. Next if your roof and windshield has snow on it. Use your arm to remove as much of the snow as possible. Once you've got the snow off, we are going to spray some de-icer on the frozen windshield. If you don't have any de-icer you can easily make your own with a simple solution of 50% water, 50% vinegar. Make sure your water is no warmer that Luke warm as hot water is known for cracking frozen windshields, and a frozen windshield is not a good way to start a day.
Spray your de-icer on the window then scrape the remaining ice off with either an ice scraper or some sort of credit card. Within 5 minutes, your car should be de-iced and ready to drive!