Beaver and Autoresponder


I am a newbie to Beaver!
Can anyone tell me how I can incorporate an opt-in form in a Beaver webpage ?
I understand there are there two methods:

  1. Using API keys to for example Getresponse, Mailchimp, etc
  2. Using html codes generate by the email software.
    Would need instructions of both cases.
    Thank you muchly.
    Soon Tan