This used to involve hanging your food from a tree branch or a pre installed cable by a length of light line. The bears have figured out how to defeat this method in may instances. The USFS Inyo National Forest is already requiring the use of Bear Canisters for camping in Onion Valley, which is east of Kearsarge Pass. This is an eastern lateral access trail to the JMT near Independence. The canisters weigh just pounds and hold from 2 to 6 days worth of food for one person.
Canisters are available to rent or buy from the Curry Village Mountain Shop in Yosemite Valley.
MT Recreation in Big Pine sells bear canisters over the net. Their page has specifications and pictures of the cans. The guidebook and your wilderness permit describe the proper method for hanging your food. Here is a rather humorous description of food storage in bear country, including diagrams of the counterbalance method and photos of what bears can do to your car at the trailhead. Includes comments from bears.