If I have congestive heart failure, how likely will it be that my child will get it as well?

Depends. Heart failure is a common outcome of the aging process due to a complex interaction of health issues. As an entity it is not inherited like eye color. Some rare metabolic conditions, storage diseases etc may have CHF in later life, but these are controlled by recessive genes & not passed directly. Obesity as a complex family lifestyle/metabolic issue can raise the risk.
CHF. There are familial cardiomyopathies associated with CHF but most causes aren't necessarily familial. Ask your doctor about what is the cause of yours and if its likely a child of yours would get it.