The round dial with the numbers from 0 to 5 at the right hand bottom is your stitch length selector, 0 being the shortest and 5 the longest. However, puckering can be caused by a large number of things that have nothing to do with stitch length. What are you sewing and what is puckering?

It could be that the tension is too tight. Try adjusting the small dial on the left side. Generally a good tension is between 4.5 and 6. Try different numbers and see if that helps. Colleen

I was thinking 'tension adjustment' as well - have you a manual?

FWIW, a wrong size/type needle/thread can cause probs as well.....

I would read the manual and practice page by painful page. I have a feeling you are a new sewer.

In the back of your manual there is a chart telling you what type of needle to use with what type of fabric.

From the picture, you look like you have it on auto tension so you shouldn't have any tension problems. I think it might be the wrong needle for the fabric, wrong size needle for the fabric, or you did a misstep in threading.