@Html.EditorFor(model => model.Screen.Description)
How to add a class or some other attributes to the generated input?
The built-in editor template is too generic (it can display arbitrary objects) for such a concept to make sense. You could either
If it's only a single property you're displaying you could use a more specific helper method such as Html.TextBoxFor():
@Html.TextBoxForm(m => m.Screen.Description, new { @class = "myClass" })