Thats where they are located, they are made by dividing the string in half over and over again which produces the same tone hence there is one at the 12th fret (its the strongest) then you divide again and one at the 6th fret that is less strong ext.
You also divide the string into other equal parts like 3rds which produces other tones. This also means that many harmonics don't fall on fret positions.
To play them you place your finger lightly on the string without depressing it (just kinda touch it like its the stargate and you don't know if your going to die).
To your right hand its the same as any other note.
You may have to move your left finger around a little bit to find the exact position of the harmonic.
Also once you sound the harmonic you can remove your finger and it will continue to sound...which makes them awesome for tuning.