To translate your teXt (or part of it) directly under Word:

Simply select the part of the text you want to translate.

Click on the Review tab (in the ribbon)

Click on the translate button

You shall get the translation options (select languages) open in a new vertical ribbon.

Select the language and click on the small green button, just below the "Translate the whole document" option.

You will be notified that the translation will be performed on httpicrosofttranslatorom/officetrans/httpquery.aspx?.

Click on Yes to proceed.

Note that: an internet connection is required in order to access the Microsoft online translation service.