After the successful installation of Chimp Your Joomla, you need to:
- head over to the Extensions > Plugin Manager
- Search for "Chimp" in the search bar
- Click on System - Chimp Your Joomla! (pro if you purchased the pro version)

By default, you will see the plugin tab and fields for both your MailChimp API and List ID.
Mailchimp API can be found by clicking on your account name > account settings as shown below:

Next, from the menu across the middle of the content area, select Extras > API key to view your API keys. If you do not have any API keys yet, you can create one here.

Copy and paste your API key into the Chimp Your Joomla plugin page where it shows Mailchimp API

Next, create or choose a list in Mailchimp that you want all of the new registrations on your Joomla site to go to.
In Mailchimp, click on list, then click on the list name of the list you want the new emails to drop in to

Now look at the URL. The ending of the URL is id=xxxxxxx where the "x's" stand for the ID number of that list.

Put that code into the line called mailchimp List ID in the Joomla Plugin page:

Now save the plugin and you're done with the Basic Setup!