Base idea, if i'm wrong please correct me it's been a year or more XD one person is climbing further up while the other backs them up from below. They continually make sure they are tied together and have a point in the mountain, aka the top person puts a kind of chisel (forgot the name sorry >. <) where he ties the rope to and the person below him removes the last one he put in. Depending on the situation they would swap places or continue if the top person had enough of those. They also use two hand picks to climb with, using them to latch onto the side and hold on to the mountain. It's a long process which could take days depending on the size of the mountain.