yeah, almost all those adds that guarantee learning the fretboard in minutes don't really offer anything good, or near worth the cost of them.

here's how you learn the fretboard. you first learn the musical alphabet, then the names of the strings, and you can "count" your way to any note on the fretboard... and with time, patience, and practice you will basically memorize where all the notes are.

so, the names of your strings are:
E (thinnest)
B
G
D
A
E (thickest)

and the musical alphabet goes: A - A#/Bb - B - C - C#/Db - D - D#/Eb - E - F - F#/Gb - G - G#/Ab - A - etc...

so just remember there are no sharps (#) or flats (b) between B and C... and E and F, and you can count your way through the fretboard.

so, for example, if we took the 5th string, which is the second thickest, and the A string, and counted up; the open string is an A, the first fret is an A# (or a Bb, essentially an A# is the exact same as a Bb, just two names for the same note) the second fret is a B, the third fret is a C, the fourth is a C#, etc.

and you can count your way from any string up to any note you want and eventually it just sticks in your head and you "master" the fretboard. but don't be fooled by adds, this is something that takes practice, not something you can learn in minutes.

If this was at all confusing, forgive me, it's midnight and I'm tired... If you have any questions, feel free to ask and I (or someone else) will gladly answer them for you! but I hope this helped some.