Penalty notice for disorder

Questions:

I have been given a Penalty Notice for Disorder (PND), 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)?

Can you tell me about the offence of 'upskirting '?