If you are having problems with forms in Wordpress, an alternative is the WordPress Integration from Hoosh Marketing.You can use Marketo-enabled forms to capture visitor data from WordPress and the forms are prefilled with data held in Marketo.
I tried to paste the iframe code into a widget and its not working... The form works when I open the landing page alone, but not when i use iframe to put it onto the site. http://www.fmjagency.com and the landing page is: http://info.sciroccogroup.com/fmjaaform.html
iFrame is by far the simplest method. If your theme uses Widgets, you can paste the iframe code into a "Text" widget and put it in the right place. Otherwise, you can code it directly into the page template as needed.
Well, it shouldn't be any different with Wordpress then anywhere else. It can be a little involved, but there are two articles, each detailing a seperate approach: