I'd recommend Lypur's Youtube channel for both theory and basic lessons. He's a goofy and awkward guy but is pretty clear and concise in his teaching. I started teaching myself a few months ago, and went on to take a music theory class at a local community college, which helped immensely in understanding what's going on (and to be able to play around with chords and melodies - even the most banal improvisation seems to impress non-musical people :) ). Don't do what I did and try to play scales/lullaby melodies for a few hours the first day you get your piano. The next day, my hands and wrists were sore, and I thought it was normal so I played on it a bit more. After a few days, I had to stop for a few weeks because of pain. Definitely spend some time working on technique and resist the temptation to play for long spats as you begin.