I'm sure you would select cardboard as your preferred wall-surface as well!
I mean, it's just so, well, durable and waterproof and sexy... right?
And for those discrimminating decorators who choose this classy paper-board option, there is only one acceptable means for joint adhesion, right?
Tape, of course.
Of the masking variety, that is to say...
Oh, and what do you need instruction for? I mean, it's cardboard, not rocket science, people:
Upside-down is the new right-side-up anyway, haven't you heard?