The FED was created because during the great recession there was a lot of controversy surrounding banks. There was no stability in the banking system, and the way for more stability was to create a central banking system known as the FED. This made is so that there wasn't just one person in charge of the banking system, but that a group of banks would work together to create one overarching system.
It was created in secrecy because there was so much controversy around the idea of banking during this time. In order for the new banking system to be non-bias and actually useful. Because of the overbearing opinions and thoughts regarding what would be a new banking system, in order for there to be the least amount of bias influence affecting the decision, they would settle this situation in private. I think this was really smart considering tensions were so high during this time due to the recession.