Not being able to read sheet music, or a strong aversion from learning musicology is one of the main reasons which holds people back from playing the piano.

Though it is perfectly possible to play the piano without being able to read sheet music (I can't myself), some theoretical knowledge of music is very important. It makes it a lot easier to learn and understand a song.

So before I'll devote myself to blogging about methods to learn and play by ear, my advice is to go through a concise musical theory course.

For example, musictheory.net offers free step by step lessons divided into topics. Going through this might take you some days, but it will make things a lot easier for you in the future.