- Piwik website: http://piwik.org/
- Piwik installation: http://piwik.org/docs/installation-optimization/
The Piwik URL is the same URL you use to access your Piwik, e.g. for the demo site: http://demo.piwik.org.
Now you need the auth token. This is some kind of secret password, which allows WP-Piwik to get the necessary data from Piwik.
The super user's auth token, i.e. a full access password for your Piwik, can be found by clicking the API link:
It is stated in the box behind &token_auth=:
The demo's (http://demo.piwik.org/index.php?module= ... =yesterday) auth token would be anonymous, but your auth token should consist of plenty of letters and numbers.
Alternativly, each Piwik user gets his own auth token. So you can choose a user's token, which comes with just the necessary user rights, instead of using the super user's full access token. You can get the users tokens at Settings → Users: