From the SDK Revit API.chm, copyelements needs an Icollection of elements ID's (Icollection<ElementIds>).
Revit has mutliple ways to refer to an element. You can refer directly to the element, you can get a reference to the element, or you can get the ElementId.
In this case, I beleive you need to get the elementid, and put it in a collection of Element Id's.
Here is the best example I can find offhand, but its in C#, and is doing something different. But it does have a collection of element ID's:
To convert to python, you have to omit the ; at the end of each line, and when you declare a variable, you don't declare the type.
I suggest starting with the simplest example possible and building on it until you get what you want.