Because this is a stitch pattern based on even numbers you need to increase in sets of two stitches. In the first photo you see a single crochet and a double crochet have been worked in the first stitch. In the second photo a single crochet and a double crochet have been worked in the next stitch so you have increased here by 2 stitches. You then pick up the stitch pattern: (single crochet in next double crochet, double crochet in next single crochet.)