Have a Necchi 3205FA and trying to figure out how to set it up for serging. DVD wasn't much help.

There is a serger attachment available for that model. When you attach it to the machine you must start the fabric from the top of the foot. The foot won't cut the fabric if you feed it under the foot. You will want to use the Wide zigzag, overlock, or hemstitch stitches. Set stitch length knob on #4 for overlock stitch #1-0 for hemstitch or zigzag. Set the stitch width to the maximum. Make sure the hook arm is inserted over the needle screw so that when the needle goes us and down the attachment will work. Start on the edge of your fabric by making a small cut about 1-2 cm deep and about the same distance from the edge as the cutting blade. This will make it much easier to feed the fabric over and then under the foot. Remember to start the fabric on top of the foot and then feed it under the foot before it reaches where the needle would penetrate.