How to chain stitch
Bring the needle to the surface at the start of the sewing line. Take it back down close to where it came up, then return it to the surface at the end position of the first stitch.
Take the needle back down, close to where it came up through the loop and bring it back up at the end position of the next stitch.
Continue working along the stitching line, repeating the steps to create a chain of links. Finish by catching the final loop with a small stitch to secure.