Before using you should open Settings -> Marketo Forms and enter your base URL and Subscriber ID. This information you can get from Marketo, or you can extract it from generated code in Marketo back-end. It looks like this:
MktoForms2.loadForm(“base url”, “subscriber id”, $form_id, callback_function);
After that you can use shortcode to display Marketo from:
[marketo id=10]
where id – is form identificator
Also developers can use function to display forms:
marketo_display_form($form_id);