This dialog asks you questions in order to build the list of word forms (i.e. the paradigm) of the word you are adding. To answer the question click Yes or No button. If you gave a wrong answer click the Anew button to answer those question in a different way.
If you are not satisfied with the constructed list, answer No to the question "Is the list of forms of the word correct?". Lingvo will try to create a different list of forms.