1. How do you know about the painting?
- I think it's beautiful.
----------------
Is this answer correct? If not, what would be the answer to the question?
That question is asking how you know the details of the painting, such as its style, its painter, the materials used, etc.
An answer could be any of the following:
-- I read about it in my art history book.
-- I studied this painter and his works in college.
-- I saw an article about it in the arts section of the newspaper.