I am currently taking Spanish classes. The easiest way I’ve found to type in Spanish is to add “Spanish” as an input language for your keyboard in Windows. Once you add “Spanish” as an input language, the Language Bar allows you to easily switch between the languages. Here is a screenshot that shows how to do it in Windows 7:
Run the On-Screen Keyboard application to see what characters your keys map to.
The process on Mac OS X is very similar. Go to System Preferences > Language & Text > Input Sources. Add “Spanish – ISO” as an input source and check “Keyboard & Character Viewer”. You can then switch language input in the menu bar and use the Keyboard Viewer to see how the keys are mapped to characters.
¡Ahora puedes escribir en español! To type accents like á é í ó ú, press the accent key to the right of the ñ key first, then the vowel.