Serpentine is a specific decorative stitch. If your machine has it, the icon for it will look like an S. Chances are if you have to ask here, your machine does not do this stitch. Here is a link to a photo of a machine that has the serpentine stitch (#21):
http://thesewingcorner.blogspot.com/...stitch-do.html
Edit: Well, I looked at the logo for that serpentine stitch again and it really doesn't look like an S. If you stitch out all the decorative stitches on your machine and none of them look like the serpentine stitch, your machine doesn't have it. Here is a photo of the serpentine stitch (do a ctl/F on your computer and type in serpentine to go directly to the section):
http://www.sew4home.com/tips-resourc...pular-part-1-4
As someone else mentioned, if your machine does not have a serpentine stitch, a good substitute is to use a walking foot and manually guide your quilt sandwich from side to side as you sew.