These covered notebooks are not my idea either (shocking, I know!) but since you can find them everywhere I’m not going to link you to a specific site.
I originally used mod podge to make the blue and green one but all the rest I used a permanent hold glue stick and it was definitely less messy!
All you do is cut out paper the size you want on your composition notebook (you can leave the color of the spine or wrap your paper/fabric all the way around) and literally glue it on.
I added a felt strip to a few of them as a closure
showing the backs