You can know all the notes on the guitar fretboard if you know these 2 things:

1:	The string names biggest string E A D G B E smallest string
2:	The chromatic scale - Most notes have sharps and B and E do not. Start at A again after G#.

Just count up one fret at a time to teach yourself.
You can then memorise it while you're playing your favourite songs!

Watch the video to help this make sense! Thankyou.