Loosen the gas trap underneath the sink and remove. To remove the gas trap, loosen the collar nuts on the pipe with your plumbers wrench by turning counterclockwise. The pipe will now come off easily.
Remove the straight pipe that comes from the floor by unscrewing the collar fitting that is close to the floor with your wrench. Pull up on the pipe to remove.
Install the dishwasher fitting in place of where the straight pipe was. Tighten down by screwing tight the collar fitting on the pipe. Install the gas trap by tightening back onto the sink using the collar nut fittings and turning them clockwise.
Put the dishwasher hose on the fitting by pushing the hose onto the drain stem and clap down using the hardware that was included. Usually, the hardware will be a metal ring clamp. Place the clamp over the hose and simply tighten with a screwdriver by turning the screw clockwise until snug.
Clamp the other end of the dishwasher hose to the dishwasher water outlet using the hardware that was included. Push the hose onto the stem of the dishwasher and tighten the metal ring clamp over the hose by turning the screw clockwise with your screwdriver until snug. Your dishwasher drain is now installed.