First open up the bin bag and cut the end so you have one double sidded sheet.

Next roll up the bag so that the open ends are at either end.

Now snip into squares. It looks better if they are uneven.

When they are all done open them up. You should have two identical strips.

Stick these strips together with clear tape.

Do this to all of them. You should have a lot.

Next measure the top of your door frame and cut a piece of paper the same length.

Next stick the strips along the paper. I forgot to take a picture of this :(

Now stick it to your door.

Done :)