_ _ _ _ _ is a mountain fold. Fold like this ^
__ _ __ _ __ is a valley fold. Fold like this V.
Cut on the solid lines.
Match up the numbers, eg. 120 glues to 120.
Use hot glue or super glue.
The tab goes under the other piece.
Hope I could help.
ALSO, VERY IMPORTANT:
It's Pepakura, pronounced PEP-UH-kur-uh, not prepekura, paprika, or paperkins.