How to create invite a friend in ruby on rails?

I want to create the ability for a User to go to a form and put a first name and email address and send an invitation via email.

When the recipient clicks on the included link开发者_运维百科 and registers, the Recipient and User are now "friends."

Is there a good tutorial to get me started on this?

See this Railscast on beta invites.

If you are using devise as an authentication solution you may take a look at devise_invitable which add support to devise for sending invitations by email.

You can start with the email thing by using rails builtin mailer: ActionMailer

Here you are: ActionMailer guide.

Check acts_as_inevitable plugin.