Mino quick link geometry adjustment, what can I do with it?
Mino is a link that changes the geometry of the bike. 

High lifts the BB (about 10mm) and steepens the head tube (1/2 degree) compared to low. 

With the link set low the bike will be more stable but less agile, especially on down hills. With it high it will be more agile but less stable, with lower chance of pedal strike (due BB height). The difference is small, and may be imperceptible to an unskilled rider.  

As far as position, the best position is the one you like. There is no right or wrong. Try it on the trails you ride, and decide where you like it. Generally DH you would probably want it low, XC high.  

It will be far more important to get the suspension properly tuned up, tire pressures and bike fit correct before worrying about the link position.