How Do I Know How To Spell The Name Of My City In English For Green Card Lottery?

I have been told that all cities need to be written the English way for the
lottery. The city I am referring to is Münster. Usually these names of the
cities are changed in English, but in this case it seems to be the same. The
"ü" is not a letter though in English. So how should I write the name of the
city?