what's the easiest way to learn all the notes and where they are on a guitar?
Once you learn a note name, just figure out where the octaves for that note are. This comes with time, I know the names of all the notes on a fretboard but it doesn't always come to me off the top of my head. I've also seen a fretboard diagram that has all the notes named on it.
Yeah, he has a good point there. Once I saw this exercise where you pick a note a day, or something, and figure out where all you can play this note on the guitar. I forget where I got that exercise from but eitherway, it's probably one of the best ways I know of.
Theory links in my sig.

Basically, learn the patterns that connect notes and you won't just learn the notes but useful patterns as well. (and these patterns make learning the whole fretboard approximately 3 times easier. )
The notes are A, A#, B, C, C#, D#, E, F, F#, G, and G#.

The strings follow that pattern, they just all start on a different note. For example, for the notes on the E string, you would start with E and continue the pattern.
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