While it is not required that you have a professional teach you (or your kids) to swim, it is highly advisable. Check with your local pool (a local college, or YMCA for example) to see what kind of swimming courses are offered. If you are unsure where your nearest American Red Cross (ARC), or YMCA is, then check online at: Red Cross (in the middle near the top there is a place to enter your zip code so that you can locate your locale ARC chapter); or YMCA (there is a box off to the left that will allow you to enter your zip code). If you choose to not have a professional teach you, you will find the requirements below.
