BMTH poster

Guys I can't for the life of me keep this poster straight, I finely got a signed BMTH poster after all these years I can't believe it, I love it buuuuuut the person I got it from told me she's never taking it out of the tube, so its been rolled up for 13 years and I can't get it on my wall, cause it just keeps on rolling it self up. so I've put a blanket and books on top of it to try and keep it down but its been a day and it still rolls up. so if anyone has ways to keep it down I would love that. Also I can't get a frame, cause its either the frame 1cm to small or its tooooo big, so I'm just gonna glue tack it up and hope it doesn't wreck it