Here are the written instructions. A picture tutorial follows.
through the un-worked bottom loop from the chain.. Draw the yarn through for single
through the un-worked loop from row 1. This joins both rows together.
from the center front and mark it with a pin or something.
It doesn't need to be exact...
slip stitch in the single crochet.
of the chain 3 space...
Hopefully the diagram and the pictures will help this all make sense..