After you’ve completed 7 total single crochets through the center ring, slip stitch into the chain 1 you made prior to working your single crochets (see photos 5 and 6). This slip stitch joins your first and last stitches and finishes the round. We will count the first chain of every round as one single crochet, which means your completed first round consists of 8 stitches.
(Not all center rings will begin with 4 chains before joining. The original number of chain stitches will vary by pattern and yarn weight. The more stitches you start with, the bigger a hole there will be in the center of your round.)