For us with german/austrian/swiss etc. keyboards it is easy, for all others, here are some
umlaute for copy-and-paste:
ö
ä
ü
Ö
Ä
Ü
You can also put those characters in by holding down the [i]Alt[i] key on your keyboard and punching in the respective numbers on the numerical pad of your keyboard (with num lock enabled)
German
ä = ALT+132
ë = ALT+137
ï = ALT+139
ö = ALT+148
ü = ALT+129
ß = ALT+225
Nordic Languages
å = ALT+134
æ = ALT+401
Spanish
á = ALT+160
é = ALT+130
í = ALT+161
ó = ALT+162
ú = ALT+163
ñ = ALT+164
¿ = ALT+168
¡ = ALT+173