On the Macintosh all the marks are built right into the keyboard. No need to do anything but type them. Just hold down the option key and while doing so type the u and then let go of the option key and type the u again to get the ü (u with umlaut). For ä (a with umlaut) do the same but type the a the second time. ö (o with umlaut) is the same but type the o the second time. This works with e and i too, but German does not need those. Option-s will give you the double s (ß). Keycaps in your Apple Menu will show the entire keyboard of whatever font you're working in. Colin