There is a way to memorize notes on your fret board....Yes it's called the caged theory..See the chord positions of these notes at the bottom of the screen....then see how these positions trail up the neck to the left A & C
Now the catch is knowing the pentatonic scale (note that there are not 2 tonics F & C  like on your piano) There are 5 positions up the neck (see "pentatonic fretboard" below) These are only the notes that you play open...without fretting   
So     E  phase is the open strum
G  is the 6 notes on the G fret
A are those six notes B & D
these six notes ascend and descend in the same order as the open fretboard E only they start at the note i've shown you ...So G is ....G.B.E.A.D,G     descending is much easier to remember
A starts at A....so memorize these postions
Now we're going to tie it all together.....the multicolored A above shows in descending order the a note (purple) see the C positions going up and the D position going down The E (green)  repeats the C position amd D....the B (oange)uses the G position going  up and the A down ...G (yellow) D up E down....D (blue) and back to A
This rule applies to every pentatonic fretboard phase   E,G,A,B,D 

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