Need to know what tip to use to make it look like rope and how to do it?

this link is to Wilton.

http://www.wilton.com/technique/Rope

I think you could also use a round tip.

You can use any of the open-star tips, depending on how thick you want the rope to look. You kind of pipe smallish slanted S shapes with the start of each shape tucked into the upper bend of each previous shape.