Soaking works best in most cases. Scrape away as much of the burned food as possible using a plastic scraper. Make a solution of water and baking soda in equal proportion. The water should be hot. Pour enough of this solution to cover the burned area. Leave the pot like this for several hours, preferably overnight. Check the food reserves in the morning if they are coming off easily. Drain off the soda solution and use a nylon scrubber with detergent to clean the pan.
If the stains are very stubborn and do not seem to disappear with the first step or the burned food has gone old and too tough, boiling the pan is the best solution. Make the same solution of baking soda and water. Now pour it into the pan and put it on the stove. Turn on the heat and boil the pan till you feel that the burnt food has loosened and is coming off. Scrape the food deposits using a plastic scraper. Wash the pan with a soft cloth and detergent to get rid of the remaining stains.
Vinegar is your cleaning tool, from floors to pans. It is extremely good at removing burn stains from pans. Make a solution of vinegar and water and wash your pan with it. It removes calcium deposits which appear as white spots on your pan. It also removes the stains left after you treat the pan for burnt food.