What do you do if im too fat to walk?

If all you can do is move your arms, start with moving your arms. If you are very heavy and unfit, you can work up a good sweat and get cardiac exercise just through basic full range of motion arm movements. Once you have lost some weight through working the parts of your body you can work, then it will be more comfortable to try to walk or do other lower limb exercises.

I would recommend doing leg lifts sitting in a chair before attempting to walk any distance, to strength the quads, hamstrings and muscles around the knee and avoid injury.

Don't worry about what you can't do...find something you CAN do, even if that's as simple as arm movement. Also consider Chair Dancing videos.

I am happy to have replaced a completely ignorant and rude answer with one that might actually be helpful to somebody.