You can download the manual for your machine from the Brother site, link ishttp://welcome.solutions.brother.com/BSC/public/files/dlf/doch000061/xr52c65txl64526562ug01enesfr.pdf
There are lots of weights of silk fabric but I'll assume you are working with something soft and silky like a silk charmeusse or silk georgette.
You need to stitch seams with a straight stitch and use a new sharp needle size 70 or even 60. Change the needle every 4-6 sewing hours or if you hear squeaking or popping; throw away the blunt one.
Use a quality polyester thread like Guttermann, Mettler, or Metryosene. Start with stitch length on 2.5 and stitch width zero (straight stitch). The normal metal presser foot is probably best for this. If the fabric is see through you may wish to do french seams to encase the raw edges. This is where you sew wrong sides together, then turn and stitch right sides together, if you have never done this instructions are here http://sewing.about.com/od/techniques/ss/frenchseam.htm
Also pay carefull attention to your bobbin winding, my tip for this is herehttp://www.fixya.com/support/r10598580-winding_bobbin_correctly
as winding the bobbin smoothly and evenly is essential to quality stitched seams.
Always press every seam as you sew, dry iron, silk setting. Press each side of the seam, then press the seam allowances open, this sets the stitches into the fabric.
If you find that the seam is pulling up you can try loosing off the top tension by a half number (turn it down to loosen) and shorten up the stitch length a fraction to 2.2 or so. But you don't want it too small as if you need to "unsew" ie unpick, you'll never see the thread.
Use a lighweight interfacing if the pattern requires it; I'd use a fusible but very lightweight such as Pellon Featherweight.