Which way to install fan on cpu cooler

[Nahtangnouv]

I dont know which way to install a fan on my cpu cooler
it is an hyper 212+ I dont know which way the fans pull the air or push the air, it really confuses me which way to install them.
I left my hyper212+ fan the original way it was placed and had it facing my back fan.
I dont know which way to place the fan on the other side of the cpu cooler

 

[USAFRet]

For a single fan on the 212+ (I have one), have it pushing into the fin array.
For dual fans, push and pull.