For C# csharp you cannot compile as given.

class Result
{
    public static SinglyLinkedListNode insertNodeAtPosition(...)
    {
		...
    }
}

You need to modify the above code by removing class Result{} block and remove the public modifer on the method.

You should be left with...

    static SinglyLinkedListNode insertNodeAtPosition(...)
    {
		...
    }

This should allow your code to compile.