I would like to implement the simple workflow:

1. Person signs up to join a group, using the Group Registration block, where they enter their email.

2. Work flow emails the person a 'Click here to confirm your email is <xxx> and you want to be in this group.'

3. User clicks the link, and is taken to a confirmation page.

4. User clicks the 'Confirm' button.

5. Workflow confirms the person's email address as active, and changes their group member status from 'Pending' to 'Active'.

I don't know how to do step 3  and 5.  I'm guessing the link in the email will have to contain the information needed to be able to find the person in the group so that I can use SQL to change the email active status and the group member status?.

Any suggestions?