NLTK and Stopwords Fail #lookuperror

I am trying to start a project of sentiment analysis and I will use the stop words method. I made some research and I found that nltk have stopwords but when I execute the command there is an error.

What I do is the following, in order to know which are the words that nltk use (like what you may found here in section4.1):

    from nltk.corpus import stopwords

But when I press enter I obtain

    LookupError                               Traceback (most recent call last)
    <ipython-input-6-ff9cd17f22b2> in <module>()
    ----> 1 stopwords.words('english')

    C:\Users\Usuario\Anaconda\lib\site-packages\nltk\corpus\util.pyc in __getattr__(self, attr)
     67     def __getattr__(self, attr):
    ---> 68         self.__load()
     69         # This looks circular, but its not, since __load() changes our
     70         # __class__ to something new:

    C:\Users\Usuario\Anaconda\lib\site-packages\nltk\corpus\util.pyc in __load(self)
     54             except LookupError, e:
     55                 try: root ='corpora/%s' % zip_name)
    ---> 56                 except LookupError: raise e
     58         # Load the corpus.

      Resource 'corpora/stopwords' not found.  Please use the NLTK
      Downloader to obtain the resource:  >>>
      Searched in:
    - 'C:\\Users\\Meru/nltk_data'
    - 'C:\\nltk_data'
    - 'D:\\nltk_data'
    - 'E:\\nltk_data'
    - 'C:\\Users\\Meru\\Anaconda\\nltk_data'
    - 'C:\\Users\\Meru\\Anaconda\\lib\\nltk_data'
    - 'C:\\Users\\Meru\\AppData\\Roaming\\nltk_data'

And, because of this problem things like this cannot run properly (obtaining the same error):

    >>> from nltk.corpus import stopwords
    >>> stop = stopwords.words('english')
    >>> sentence = "this is a foo bar sentence"
    >>> print [i for i in sentence.split() if i not in stop]

Do you know what may be problem? I must use words in Spanish, do you recomend another method? I also thought using Goslate package with datasets in english

Thanks for reading!

P.D.: I use Ananconda

You don't seem to have the stopwords corpus on your computer.

You need to start the NLTK Downloader and download all the data you need.

Open a Python console and do the following:

    >>> import nltk
    showing info

In the GUI window that opens simply press the 'Download' button to download all corpora or go to the 'Corpora' tab and only download the ones you need/want.