Brush PVC primer onto the end of the soil pipe that is visible when looking down at the floor. Brush additional PVC primer onto the inside of the floor flange.
Brush PVC cement onto the end of the soil pipe and onto the inside of the floor flange.
Push the flange down onto the soil pipe, twisting it as you push until the metal collar of the flange is resting on the floor.
Twist the collar of the flange until its slots are lined up with the wall behind it. Do this quickly; the cement sets up very fast after the flange has been pushed in.
Drive screws through the flange collar into the subfloor below. There are holes in the flange collar designating where the screws should be installed. Do not install screws in the elongated slots in the flange collar, only the holes.