Welcome to FitDay and the forums.
Losing over 100 lbs seems almost impossible, I know, but I'm here to tell you it really isn't.
If you commit, and it sounds like you have, you CAN do it! Decide on your eating plan, figure out your daily calorie burn and what you want to run for a daily deficit and use FitDay to log everything without fail. Get in some exercise, drink lots of water and it will happen.
There are a couple of 100+ to Lose threads here (one in the Women Only subforum and one in Weight Loss Tips) if you want to talk to others in your situation. If you have any questions or would like advice, please don't hesitate to ask.
47 M 5'8"
May 4, 2010...... 440? lbs. (Start FitDay Size 60 Jeans)
June 19, 2010.... 393 lbs. (First Weigh-in)
June 19, 2011.... 229 lbs. (164 lbs. gone in one year :-)
Current Weight... 185 lbs. (Size 36 Jeans)
Next Goal 169 lbs. (07/04/12)
Ultimate Goal 165 lbs. (12/31/12)
The best exercises for weight loss are Fork Putdowns and Table Pushaways.