Mikrotik up with PPPoe server!

Hello,

My new Mikrotik is up and running.. just wanted to ask a few questions:

  1. How to I secure my router from not being hacked or others trying to hack it ?
  2. How to configure the firewall, what to Drop and Accept? I have no idea what to Drop and Accept . and I dont want to leave it as it is.

Please answer thinking of me as a 5 year old! new at this!

Cheers