MailChimp integration in php - urgent


Is there any way how to add MailChimp Integration straight into php code not by widget? I haven't found it myself in usage. I need only it really simple: an email field (with some watermark/placeholder text) + a submit button and I need to place the alert box under the form. Widget is too complicated and I need to use unnecessary css for it.

Or any shortcodes?

See a sketch of it.