What is the quickest way to learn piano well?

I am going to give you the benefit of 37 years as as a professional competition judge, clical performer, and certified teacher - and give you the OBVIOUS answer that you know anyway - GET A TEACHER!! There are MANY of us who are highly trained in working with people at all levels of previous experience. There are NO websites, etc. that will help you they cannot HEAR you, can they? So ask around, call around - maybe start with a local college music department, or even the music department chair at your local high school who can refer you. I applaud your interest and your desire to proceed with this! Good luck!