Measure the size of the plexiglass that comes with the window installation kit and open the window to that height. Set up the portable air-conditioner next to the window and make sure the electric plug is close enough to an outlet that it can be plugged in once the unit is installed to the window.
Attach the plexiglass window insert to the opening in the window. Screw the insert into the frame of the window on both sides with a power drill. Snap the window adapter over the plexiglass in the opening. Line it up with the holes in the plexiglass and attach it in place.
Install flexible hose to the rear side of the portable air-conditioner. Insert the hose collar on top of the exhaust unit and twist it into place to lock it in position. Repeat the process for the hose on the other side of the unit.
Attach both hoses to the window adapter. Snap them into place in the adapter and move to the outside of the house to make sure the vent is reaching the outside. Lock the double-hung window into place so it cannot move up and down. This could cause the window kit to fall out.
Plug in the air-conditioner and turn it on to make sure it is working. Check outside once again to make sure air is venting out and verify that the room is cooling down.