The Federal Reserve has finally raised its interest rate. The impact on savings accounts won't be huge, at least for now. However, with the December increase, the fed funds rate - which has been circling zero for the last six years - went up a quarter percent. Though this is a baby step, bigger changes could come in 2016 if the Fed continues to raise rates. So here's what millennial savers and borrowers should know and more improtantly, what to do about it.