Certified Flight Instructor Instrument CFII
To fly in the clouds, you'll need to be instrument rated. This is an add on rating to your private or commercial pilot certificate. You must have at least 50 hours of cross country flying logged to be eligible for the practical test. It requires a minimum of 15 hours of dual training with a CFII flight instructor and a minimum of 40 hours of simulated instrument flying. You can log simulated instrument time with another private pilot acting as your safety pilot. You'll have to take another written exam and another practical test (check ride) to complete this rating.
Instrument Proficiency Check
The FAA requires that all instrument rated pilots maintain currency by continually flying in actual Instrument meteorological conditions (IMC) or by simulating this with a safety pilot or instructor and a view limiting device. If you haven't maintainted your currency, or you simply don't feel proficient and want to get more training, you can do an instrument proficiency check to get you back to flying by instruments safely. Your IPC will be tailored to suit your situation.