Remove the glass from the window. If you have a divided window, you only have to take out the glass on the side that you will use to vent the dryer. Measure this area and cut a piece of wood that will slide into the opening. The wood should be snug.
Mark the center of the piece of wood. Then drill a hole so you can insert the saber saw or use a hole saw to make a 4-inch hole. After the hole is made, fit the dryer vent hood. This should be a snug fit as well. Use the caulk and caulking gun to seal the area around the flat piece on the vent hood to the piece of wood.
Place the piece of wood in the window. Use the caulking gun to place a bead of caulk around the edge of the wood where it meets the window frame. Once the wood is secure in the window and the vented hood is secure, you are ready to add the elbow.
Place a 4-inch pipe elbow on the inside opening of the dryer vent hood. Position it so that it is facing the direction of the dryer where you will run the long 4-inch dryer pipe to the bottom of the dryer where the outlet vent is. Use the foil tape to seal the elbow to the vent hood.
Add the long piping to the elbow. Use the foil tape to seal the connection. Then go to the other end of the pipe. You will more than likely need to add an elbow to the output vent on the dryer to connect the vent pipe. Add elbow and seal it with the foil tape. Then connect the piping to the elbow and seal with the foil tape.
Turn on the dryer and look for any leaks. If you followed the steps correctly, you should have no leaks. To determine if you have a leak, run your hand around the pipe as the dryer is running. If you do feel air coming from the taped joints, use some more foil tape to seal the leak. Then walk outside and make sure that the flap on the dryer vent is opening when the dryer is running.