Penalty notice for disorder

Questions:

I have been given a penalty notice for disorder, does that mean I have got a criminal conviction?
I have received a letter with regards to a fine from HM Courts & Tribunal Services regarding a road traffic offence that I am alleged to have committed. I know nothing about this offence. What should I do?
What are penalty notices for disorder (PNDs)?

My car has been stolen, what should I do?