All you have to do is take the bag you've been provided (really, any bag will work) and fill it with non-perishable food items. Then, place the bag near your mail box on Saturday morning and your carrier will gladly pick it up on his or her route. The food will be provided to local food banks and shelters.
If you don't get your food out in time, you can drop it off at any post office.
Stamp Out Hunger, sponsored by the National Association of Letter Carriers, collected more than 77 million pounds of food last year. They're hoping to beat that number this year, so jump on it!