Upload the entire chimpblast folder to the /wp-content/plugins/ directory.
Activate the plugin through the 'Plugins' menu in WordPress.
Visit the options page to configure defaults. You must log into your MailChimp.com account and obtain an API Key. From the MailChimp dashboard, look under Account, then API Keys & Info.
Customize the template as necessary. The Chimp Template is a submenu under ChimpBlasts. You can download templates you use on MailChimp.com and load them here. We provide a few suggested stylesheet tweaks for compatibility with WordPress formats.