You certainly seem to have both dictionaries (en-GB, british-english, and es-es, spanish) installed correctly, no problem there. You didn't mention which version of Firefox that you installed basically, the english or the spanish version, but I'll assume english here - it may not even matter, as long as both dictionaries are installed correctly, they should be usable. When you enter text in a text area, you should be able to right-click in the area and from the context menu have a point "Language >" under which you can select which dictionary to use on the page. To make it even more practical and user-friendly to yourself, I can strongly recommend a Firefox Add-on that I use myself for controlling dictionary selection; the Dictionary Switcher addon. You can get it here: [https://addons.mozilla.org/firefox/3414/ Mozilla Addons] or [http://en.design-noir.de/mozilla/dictionary-switcher/ Authors homepage]. I hope this is helpful to you - if not, please let us know so we can investigate where this fails, and include any detail you can come up with that could help us track down the problem.

See also [[Using the spell checker]]