How to put up peel-and-stick wallpaper?

Rebecca

Hi all, I put this up about but it was soo difficult for me! I had the hardest time lining up the sheets and from keeping it from bubbling. Also after 2 years it's starting to come off especially this summer while it's been so humid. Does anyone have any advice on how to put up peel-and-stick wallpaper better and how to keep it from getting bubbles and wrinkling? Thank you!