Move your thumb over little by little and make six creases.
Move your thumb over little by little and make six folds.
「親指を少しずつずらしながらひだを6個つくります。」は英語ではこのようです。
Move your thumb over little by little and make six creases.
Move your thumb over little by little and make six folds.
「親指」→ thumb
「少しずつ」→ little by little
「ひだ」→ crease, fold
ご参考までに。