You should modify SinCreator.elm.
It is called from Main.elm, but do not modify Main.elm. Your submission must compile against the existing modules, with your new SinCreator.elm dropped in.
Other modules can be referred to as examples.
Submit your code on Avenue, with your names and student numbers.
If you want to contribute your changes back to the main ShapeCreator, say so in a comment at the top of your module.
elm init elm install MacCASOutreach/graphicsvg
elm make src/Main.elm