Alternatively, you can find the em dash in Microsoft’s symbol settings. Find the insert setting in the upper-left corner and then the omega (Ω) symbol in the upper right. Select that symbol ...

Do not use a hyphen in place of "to" or "through," except in dates. A dash is expressed as an "em dash" ( — ) in printing, is expressed in plain text as two hyphens ( -- ) and is used in place of a ...