I have found a fix offered by Agustín E. Bolzán in a message
11/28/2003 to the problem of installing the elsart.cls package. 
... 
>>  put elsart.cls in localtexmf\tex\latex\elsevier and refesh the file
>> name database.

>> That's all

>> Agustín E. Bolzán
 
However, now when I try to use Winedt, it does not recognize my .tex files.
Has the manual update caused this problem?
 
Thanks,
 
Ana Ferrando