Are there any good sites (similar to this one but for piano/keyboard) for online lessons and everything related to playing piano and keyboard? Trying to teach myself but a good site would help me on the way!

easy piano lessons on youtube is brilliant

learn chormatic scale, c major and aminor both hands all octaves
and learn triads
then learn easy melodies in c major etc with left hand triads.

Whatever you do, just make sure you find a place where the people can play and teach well. Watch out for all those "how to play muse on piano" videos and whatnot, so many of the people who make those videos have useless technique, bad timing, aren't doing it properly, and will just get you into bad habits.

It's always good, even if your goal is to play rock piano to hit the classical stuff as well. It forces you to read more difficult music and really gets your fingers working.

I recommend picking up some piano books, you can get graded ones to start you off (Choose grade 1+2 if you're an absolute beginner, grade 3 after that, etc.) otherwise there are lots of other options. Just make sure you're playing lots of music and not just learning from youtube.

It would be a good idea to also get a book on scales and arpeggios, not so much for the notes but to get you into good fingering habits. Of course some rules can be broken and there's no "one way" but it's worth learning the old proven methods before you decide otherwise.

Anyway good luck.