How to hang food using the counter balance with retrieval cord method.
Pick appropriate tree and branch. In bad bear areas a proper tree may dictate where you camp. As you near timber line there may not be tall enough trees, so you must plan ahead. The limb should be about 20+ feet from the ground. Higher is better as bears are less likely to jump off a limb onto the bags if they know they will take a long fall. The bags should hang about 10' out from the tree. Where the rope goes over the limb, the diameter of the limb should be about the size of your wrist or smaller. Larger and they can climb out the limb, smaller and they can break or chew through the limb. Some bears can get any food hang too. Check with local authorities about food storage methods. Food hangs work best with wild bears that have some fear of humans.
Camping with groups, I have had to hang as much as 200 lbs of food each evening. It can take several hours, and several trees, to do it right for that much food. A bear resistant canister may be a safer and easier choice for some folks.
Quick Sketch of food hang with retrieval cord (Note the cord ends must be seperated on the retrieval so that the bear can't just grab both ends in his teeth.)
US Park service drawing of bear hang without retrieval cord.