I taped up my posters but they keep falling off, suggestions? I don't want to use staples or tape on the front

Real simple.....cut some strips of hard cardboard about 3" wide cut two strips 1"for tape or 2" for pins,longer then the length of the poster and two strips the same way wider then then poster. cut all corners on a 45 degree angle,tape the corners together on the back creating a picture frame.Tape or pin your frame to the wall on 3 sides, slide your poster in and close. You could even protect your posters by sliding a thin clear plastic in front........you will never get a better answer then that......regards