You need to know this at least:


Basic things about piano is the left hand is bass (rhythm) and the right hand is for melody. So if you play piano keys from left to right you will get from a low pitch to a high pitch sound.

So piano chords are the same with the guitar. Most of the time piano chords are 2 to 5 notes (basically I always plays with 2 or 3 chords notes). Pianist plays the chords mainly on the left hand.

Piano melodies, just like playing solos on the guitar.

You can start charting the piano notes. It is better to take piano classes. It is hard to be a play-by-ear pianist, better read notes and charting them one by one.

One more thing, everything starts from slow.