C# xml writer checkbox checked

I built a program program that generates an html file with an xml file. How do I make to input type='checkbox' id='hi' checked/>? How do I write that checked in C#? I did not find anything on google. That's what I have:

XmlElement Check = doc.CreateElement("input");
                Check.SetAttribute("type", "checkbox");
                Check.SetAttribute("id", "hi");