"I do not like the chairs." (the "best" translation, at the top of this page) and "I don't like the chairs" are the same, and both should be accepted if they are not already.
Yes, szeretem is definite. It's required here because the object is a székeket, the chairs, with a definite article.
Szeretek is indefinite conjugation. But you have a definite direct object here, so you need to use the definite verb form.