anyone fancy teaching me guitar?

ok so back on topic, i've noticed my 'annotations' are out of tune, when i pluck an open string its pefectly tuned but when i press the 12th fret its not in tune but it should be
its called a harmonic or something?
how do i fix this myself without paying a guitar dealer to fix it?
 
ok so back on topic, i've noticed my 'annotations' are out of tune, when i pluck an open string its pefectly tuned but when i press the 12th fret its not in tune but it should be
its called a harmonic or something?
how do i fix this myself without paying a guitar dealer to fix it?

Intonation*.

Google a guide.