Cut off a piece of thread at least 20 inches long. Thread it through the needle and pull the sides of the thread so they are even.
Push the needle through the foam in the unfinished back of the leather chair. Push the needle through the place you want to sew the button. Leave a tail of thread about 4- to 5-inches long.
Thread the needle through the back of the button two to three times. Push the needle back into the foam and out the back of the chair.
Pull the pieces of thread tight so they create a tuft. Tie the loose ends of thread into a sturdy knot and staple the ends in place.