It's not a silly question! Inquiring minds want to know!
My Bernina 1230 has a serpentine stitch, so I would imagine your
janome dc5100 has one too. I Googled images of your machine and came up with this one for stitch selection: http://www.gallsewingvac.com/Images/...100lidW550.jpg
It looks like stitch #52 is similar to what I have on my Bernina. I can adjust stitch length and width to get the look I want at any given time. The other two stitches on your machine may be similar, but I can't tell for sure from the photo. Stitching each one out at default settings, then playing with stitch length and width, should give you a good idea of your options.
This website shows some variations of the serpentine stitch: http://snarkyquilter.wordpress.com/2...k-you-jacquie/ but she says her Janome doesn't have as nice a one as her friend's Babylock. (I have no idea how the Babylock serpentine stitch compares. The samples on this page look very similar to what I get with my Bernina.)