How does someone get congestive heart failure?

Weak pump: For whatever reason - a 'heart attack', alcohol, virus, other disease - the heart doesnt pump as well as it should, and, simply speaking - blood backs up and 'congests' everything behind it - so your lungs, liver, and legs are congested - that might cause shortness of breath, liver damage, and/or swelling in the legs. Think of it as a sump pump gone bad - water backs up in your basement - etc.

Weak heart muscle: A weakening of the heart muscle from coronary artery disease, too much alcohol or a viral infection weakens the heart muscle leading to chf. Find the cause first, then the treatment follows. See a good cardiologist, plenty of good ones in palo alto.