For this, I peeled off the white strip and placed the new adhesive (with blue template still on) onto the inside of the back cover, making sure it aligned. I then peeled off the blue sheet and applied pressure and a mostly-cooled iOpener to help it adhere. Worked very well for me.

Really comprehensive, helpful and well-written guide. I prefer to learn to fix things on my own, so this was immensely helpful and just what I needed. Thank you so much!