What do buddhists believe happen when you reach Nirvana/Enlightenment?

When you reach Nirvana/Enlightenment, you just simply attain the ability to not be attached to your thoughts. For instance, if my brother called me a name that I did not like, and I let it go after it happened, that would be a person who has attained nirvana/enlightenment. An enlightened person doesn't dwell in the past or the future because the past is an attached thought and the future is an attached thought. The present moment is all you have, and nothing can make you suffer in the present moment because there are no attachments to thoughts in the present moment.