It sounds like you came extremely close to blacking out. This is caused by lack of oxygen to your brain. Other parts of your body were using up your oxygen supply faster than your lungs/heart could supply it.
Not a good thing.

I recomend the following.
1. Go see a doctor for a physical checkup. Tell him you want to start an exercize program, tell him your goals and what type of exercizes you intend to do. Get him to OK your program.
2. Discuss your goals and the results of your visit with your doctor with a certified trainer. Have him set you up with a program based on your current physical ability. Learn how to do the exercizes properly (including when and how to breathe) Learn how to listen to your body. Work out with that trainer until both of you think you are ready to exercize on your own.
3. Go back and work with your trainer from time to time, so you can adjust your workouts as necessary for your rapidly improving new body.

Good luck, you can do this.