At this point you are going to fold the paper, on each and every score mark, forwards and backwards, using your bone folder to really crease the paper. The purpose of this is to make each fold as flexible as it can be so that the pages will open up and lie flat when the spine is in the album. So, start at one end, with the first score mark, and fold it one towards you and crease really well, then fold it away from you and crease really well. Move on the the next score mark and repeat,,,,, all the way down the line.
To blameless the spine, pull the backing from ONE piece of tape at a time off and fold the two wide sections together so that you have a ridge that looks like this. Repeat 8 times.
Next step: Clip the corners of each ridge, on both sides, then add 1/4" score tape to one side of each ridge. The tape will allow you to add your pages later on in the assembly process.