Type the "umlauts" and the "ß" like this:

Press and hold down the "ALT" key. While you hold it down, type the following number combinations on the keypad. Then release the ALT key and the respective letter should appear on your screen.

ä – 132      Ä – 142       ß - 225
ö – 148      Ö – 153
ü – 129      Ü – 154

You have to use the keypad for this (using the row of numbers at the top of your keyboard does NOT work).

An alternative is to use the pull-down menu from your word processor: go to "insert", then "symbol". If you don't see the umlauts and the ß, change the "subset" or the "font" until you find a set that contains the umlauts and ß. Be sure to pick the right ones (there are characters from many languages, some look similar, but they are not the umlauts; umlauts have two dots on top).