Entering German Characters
Unfortunately there is no easy answer to how you enter German umlauts on your keyboard. The problem is that there is no standard method for entering ASCII characters higher than 127. So every manufacturer chooses a solution, so there is standard answer. Exactly what you should do will vary with your computer, your operating system, your language and the font you are viewing this page with.
I'm told that on some IBM compatibles, you may enter am umlaut by holding down the Alt key and typing a decimal value for the character on the numeric keypad. This does not work for me on any machine I try, but perhaps it'll be useful for you.
Here are the decimal values for the German characters:
Another, sure fire, but clumsy technique is to highlight the single character you want to type, and then copy/paste it into the text form you are using. Ugly, but at least it will work.