Activating tildes and accents for a USA keyboard layout in Ubuntu

Wow. This time the title of the post may actually be longer than its contents. How do you enable accents and tildes in Ubuntu? You need it to type cool characters like á, Ó or ñ (hey, my name has one of these!).

If you are on Windows I think you have to install a new map, and then guess where the key would be. Or use an alt+something magic spell. In Ubuntu, it works by default you just need to add a compose key, Go to System > Preferences > Keyboard > Options > compose key position, select right alt (or whatever you fancy), there you go, now it works. Try it by typing alt + ' + a.