If you were going to work Tunisian simple stitch, the next step would be to work stitches into the vertical bars all the way across the next row. You're not going to do that here, but the vertical bars create an important frame of reference.
There's a vertical bar below your active loop, but you can't really do anything with that one, so just ignore it and use the next closest vertical bar as your reference point. Using your crochet hook, you're going to pierce the fabric completely through from front to back, as shown in view R, and the spot to do it is directly to the right of the vertical bar. (View Q.)
After you've pushed your hook through the fabric, yarn over and pull up a loop. If your hook went in at the correct spot, the result will look something like view S.
Continue pulling up loops in this manner all the way across the row.
Next Page: Working more rows of Tunisian knit stitch