Print 8.5 x 11, single sided, 100 percent scale, heaviest stock the printer takes

Score the four dashed lines: top tab, apex, base, bottom tab

Fold 1 top tab folds under the back face

Fold 2 apex folds, back face comes up over the front face

Fold 3 base flap folds under the front face and rests on the counter

Glue both tabs, inside, hidden

Note the back face is printed upside down on the flat sheet on purpose. It reads right once folded.