I would think you need to create a viewdata or create a viewmodel to include a select list passing in a drop down list. For example, in the action of your controller, you should do this:
ArrayList countryList=New ArrayList;
foreach (Country c In YourCountryCollection)
{ countryList.Add(New With {.Item = c.CountryName, .value = c.CountryID})
}
Viewdata("CountryList")=New SelectList(countryList, "Value", "Item", itemToEdit.countryID)}
, , html.editorfor :
Html.Editor( "CountryLis", "CountryDropDown" )
.
.