Ah, very nice. For the next 2 sts you’re going to work an increase by knitting into the bumps in front of the sts. Knit into the first bump and then knit into the 2nd. You’ll have 2 new sts (the increases) on the right hand needle. Now knit the next 2sts.
Welcome to KH! @MochiMoto Did the pattern work out for you?
Mamgu, have you tried this on a swatch or some scrap yarn? You’re making the cross by knitting into the stitch below, then again into the stitch below. The 2 original sts remain on the left hand needle. Keep the stitches fairly loose so that the second increase and the subsequent sts aren’t a struggle. Finish by knitting the 2sts that are still sitting on the left hand needle.