When you make your very first pattern repeat, you will be just knitting the stitches if the previous row through the back loops (you can even knit them through the front loops, if you want). But when you get to the second part of the pattern repeat, and through the rest of the scarf, you will need to knit a series of yarn overs through their back loops. I’ve found a small trick how to make that easier, and here it is: