I agree with @Thavron@[email protected] 's comment. Before getting too deep i think just grab a pen and paper, better if it's a cheap sketchbook and start drawing whatever you want. Do not worry about nothing. Just draw. Over time not after too long you will start to discover your interests and favorite ways of drawing. I think asking here after that position where you know what you are looking would be better. There are endless amounts of resources online however they amount to nothing if you do not know what to look for.
So. Start drawing. Have fun. Then come back here.
Do you know the name of the art piece ? I really like it.