This video covers how horizontal window blinds work. The mechanism that allows this to work is at the very top. The cord lock allows the blinds to be held up by pinching the lift strings between two rollers.
source/image: Jared Owen
The tilting of the blinds is handled by the wand tilt mechanism or the cord tilt mechanism. These mechanisms turn the gears, which turn the rod, the drums, which pulls the ladder strings to tilt the blinds.
There are two main functions on horizontal blinds: lifting & lowering and tilting. First, this video from Jared Owen demonstrates the lifting and lowering, explaining where the lift cord is tied off.
The video follows the path the cords travel and see exactly how the cord lock pinches the cords in place, holding the blinds in the up position. Next, the video shows the inside the tilt mechanism revealing the gears that tilt the slats open and closed.Jared Owen