Create a shortcode

Hey Everyone,

Just a simple question, how do I create a shortcode to display a form on a page?

I’ve written the form code in php & html & have uploaded the plugin files, all I need to do is write the shortcode.

What I have so far is;

function add_contact_form() {
return ” here is all the form code “;
}

add_shortcode(‘add_contact_form’);

What am I missing?
Thanks in advance.